David Cameron:"I have discovered an inadvertent error"
David Cameron has repaid nearly £1,000 he had claimed on expenses after what he calls a "thorough review" of his claims by his office.
The Tory leader had already announced he would pay back £680 which he claimed for maintenance costs - including removing wisteria from a chimney.
But he has paid a further £267 after noticing a series of errors in claims.
He said he was "very sorry" about the claims which he described as an "inadvertent error".
The news came as details of all 646 MPs expenses claims were published on Parliament's website but with many crucial details blacked out.
BBC political correspondent James Landale said Mr Cameron's team were keen to draw a contrast between his "greater transparency" and the censored version of claims.
In a letter to the Commons fees office, the Conservative leader said: "I would like to make clear that these were discovered as a result of a thorough review by my office, not as a result of media enquiries."
They include an overpayment of £9 on his electricity and gas bill from 2007, which he said was due to a change to his direct debit payments.
I am very sorry about making a mistake like this but I think the best thing to do when you discover it is to deal with it as quickly as possible
He said he had claimed £22.50 for work related calls made by a researcher on his mobile phone - but had noticed he had actually been reimbursed £32.50 - an overpayment of £10.
He claimed £146.88 for the costs of hosting and running his constituency website - but was later asked to remove a party political page by Commons staff.
However he said he noticed the cost of adding the page in the first place - £29.38 - had not been refunded at the time.
And he said he had spotted "an inadvertent administrative error" in which he had been overpaid £218.91 for mortgage interest payments.
He said it had been caused by "the numerous changes to my monthly repayments during the latter part of the year" when a fixed rate deal ended and he later switched mortgage providers.
Mr Cameron told the BBC it had taken a while to check over the mortgage claim as it involved going through his statements, bank accounts and Fees Office details.
"It was quite complicated, it took quite a lot of time to get to the bottom of it, I wanted to get it right," he said.
"I am very sorry about making a mistake like this but I think the best thing to do when you discover it is to deal with it as quickly as possible."
After the expenses claims were published on Thursday morning, several websites reported that Mr Cameron claimed £564 to "rework photos on his website".
A spokeswoman said he did claim for work to his website but it was unfair to describe it as being work on photos of himself.
"The work was to help people with reduced visibility to see the site," she said adding the costs of the site were now met entirely by the Conservative Party.
When the Telegraph began publishing its revelations about MPs' claims in May, Mr Cameron announced he would repay £680 for repairs to the property, which included clearing wisteria and vines from a chimney, replacing outside lights and resealing his conservatory roof.
He said it was "the only maintenance bill I have claimed in eight years" but added: "Looking back, maybe that's borderline so let's pay it back and be done with it".
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