Conservative leader David Cameron: "We have to acknowledge how bad this is"
Expenses claims made by Conservative MPs have been revealed, with dog food and a lawnmower among the items listed.
The Daily Telegraph reports that shadow Commons leader Alan Duncan recouped £4,000 for gardening costs, including overhauling a ride-on lawnmower.
It also reports the shadow cabinet's David Willetts claimed more than £100 for workmen to replace 25 light bulbs at his home after electrical problems.
Tory leader David Cameron said it was time to admit the system was "wrong".
Plans to set up an independent auditing body for claims are expected to be outlined on Monday.
The Telegraph has been running leaks, hitherto largely of Labour ministers' and MPs' claims for their second homes.
Its reports of Tory expenses claims include:
More than £2,000 received by Conservative policy chief Oliver Letwin to replace a leaking pipe under a tennis court. He responded: "I was served a statutory notice by the water company to repair the leaking pipe, which runs underneath the tennis court and garden. No improvements were made to the tennis court or garden."
Shadow universities secretary David Willetts' claim of more than £100 for workmen to replace 25 light bulbs at his home. "We had problems with our lighting system which had caused many lights to fuse and needed the attention of an electrician," he said.
Thousands of pounds for renovations claimed by shadow home secretary Chris Grayling at a London flat 17 miles from his family home. He said: "In addition to serving my constituents, I have spent several years serving in the shadow cabinet, currently as the shadow home secretary. A second home enables me to meet those commitments." In response to an allegation that he delayed claims to maximise what he received, he said all claims had been submitted "at the point which I received the invoices".
Reimbursement of £4.47 for dog food to shadow Welsh secretary Cheryl Gillan, who said the claim had been made in mistake and would be repaid.
Following the newspaper articles, Mr Cameron said it was "another bad day for Parliament and, frankly, a bad day for the Conservative Party".
"We have to acknowledge just how bad this is. The public are really angry and we have to start by saying, look, this system that we had, that we used, that we operated, that we took part in - it was wrong and we're sorry about it."
Shadow defence secretary Liam Fox told BBC Radio 4's Today programme: "The last few days have been deeply damaging for politicians of all parties and the public have every right to be angry about the issue."
BBC political editor Nick Robinson said the public's idea of MPs being "honourable members" was now "dead".
According to the Telegraph, a £3,194 bill for gardening submitted by Mr Duncan in March 2007 was not paid after officials said it might not be "within the spirit" of the rules.
In a letter, the fees office said gardening costs were intended "to cover only basic essentials such as grass cutting".
But the paper said Mr Duncan, who oversees party policy on MPs' expenses, recouped £4,000 in expenses for gardening costs over three years.
If the reports are in all cases correct, then there clearly are instances where MPs have lost contact with the difference between right and wrong
In March 2007, he claimed £598 to overhaul a ride-on lawnmower, the Telegraph added.
Mr Duncan challenged the report, saying he had consulted officials about what could and could not be claimed for.
He also said he had been the first MP to publish his expenses on his website.
Shadow cabinet office minister Francis Maude claimed almost £35,000 in mortgage interest payments on a London flat that he bought, close to a house he already owned and then rented out, the Telegraph reports.
Mr Maude said: "The London house I rented out had been bought, renovated and furnished with our own money, with the exception of a modestly priced replacement bed.
"The new flat purchased was therefore properly designated as our second home and enabled me to carry out my parliamentary duties. It was also renovated and furnished entirely with our own money."
The Telegraph alleges that shadow health secretary Andrew Lansley changed his designated second home in order to claim more expenses - a tactic known as "flipping", which Mr Lansley denies.
The paper reported that he spent thousands of pounds renovating a country cottage before selling it, then designated a London flat as his second home and claimed for thousands of pounds in furnishings.
In a statement, Mr Lansley said: "Until late 2005, my main family home was in London as that is where I spent the majority of my time.
"In late 2005 my daughter started at nursery school in Cambridgeshire and from that point onwards my constituency home became my main residence.
"In my view it would have been contrary to the requirements of the ACA (additional costs allowance) if I had not switched the definition of my main residence at that point. All subsequent claims reflect this legitimate change in my arrangements."
Shadow schools secretary Michael Gove strongly denied "flipping", after the Telegraph reported he had spent more than £7,000 on a London property over five months in 2006, before claiming more than £13,000 on a Surrey property.
Mr Gove responded that his principal home had been in Surrey since before his election in May 2005. A London property that had previously been rented out was designated as his second home from later that year, he said.
Plans for an independent auditing body to oversee MPs' expenses claims are expected to be approved on Monday, following weeks of damaging stories.
Senior Labour MP Sir Stuart Bell said the Commons would be asked to approve the body, made up entirely of independent people.
Energy Secretary Ed Miliband said: "I think that most of the people who go into politics... are in it for the right reasons and are not on the take.
"But the problem is that the last few days has suggested otherwise. That's why the test of us now is do we show, reaching across parties, an ability to reform this system and get it changed as soon as possible."
Sir Stuart said an independent audit body - separate from the Commons fees office which agrees the claims - would be set up to analyse "every claim that is made".
The fees office is overseen by a committee made up of MPs and independent people - who in turn are overseen by the National Audit Office.
The new body would be entirely independent and cost about £600,000 a year to run.
Millions of receipts backing up all MPs' expenses claims under the second homes allowance were due to be published in July after a long Freedom of Information campaign.
But details have been leaked to the Telegraph - which has been publishing selected excerpts over the last few days.
Elsewhere, it has been reported that Conservative MP James Gray claimed £60 for wreaths to be laid at Remembrance Day services.
In a statement, Mr Gray said the story was "simply not true", adding: "It is in fact a rehash of a very old newspaper story from 2003, when I put down a parliamentary question to ask the then Leader of the House of Commons, Peter Hain, whether or not wreaths laid by MPs in their official capacity were regarded as an official expense.
"He replied that they were not, as a result of which I have not, and would not, claim for them."
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