Mr Brown is attempting to draw a line under the row
Prime Minister Gordon Brown has apologised over e-mails sent by his former aide Damian McBride.
Speaking on a visit to Glasgow, he said he was "sorry about what happened" and took "full responsibility".
The Tories said it was "good" Mr Brown had apologised but they still wanted a "proper examination" of the facts.
Mr McBride resigned after making unfounded personal smears about senior Conservatives in e-mails sent to former Labour Party adviser Derek Draper.
Mr Brown has sent handwritten letters to the politicians smeared in the e-mails, expressing his regret for what had happened and telling them that the rules for political special advisers would be toughened up.
But the move failed to quell the anger among senior Conservatives, who called for a "change of culture" at the top of government.
Making a fresh attempt to close down the row, Mr Brown said: "I take full responsibility for what happened. That's why the person who was responsible went immediately."
Speaking on a visit to the Govan shipyard, he said: "I have said all along that, when I saw this first, I was horrified, I was shocked and I was very angry indeed.
It's come a little late, this apology. It's a shame we had to ask for it
"I think the most important thing we do is reassure people everything is being done to clean up politics in our country.
"I wrote to the people who were affected by it and expressed very deep regret for what happened."
Mr Brown is in Glasgow for a special meeting of the cabinet which focused on the economy.
He said: "We have now got to get on with the job of creating opportunities for people and apprenticeships, creating new work and, of course, getting a budget for jobs."
A Conservative spokesman said: "It is good that Gordon Brown has apologised but he should have done it when this first emerged.
"And it still does not take away the fact that we want a proper examination into what has been going on at Downing Street."
The e-mails at the centre of the row contained allegations about Tory leader David Cameron, shadow chancellor George Osborne and others which, it was suggested, could be published on a planned Labour-backed gossip website called Red Rag, which was never launched.
Mr Osborne told BBC Radio 4's World at One: "It's come a little late, this apology. It's a shame we had to ask for it.
"We need to move on to the real issue - how we're going to clean up the centre of our government."
He added: "It was pretty unpleasant, I'll be honest. It's not a nice thing to go through.
"Of course there's rough and tumble in politics and you get very used to it if you're in the front line of politics, but this went way beyond that, and was pretty personal."
Mr Draper has said he "deeply" regrets responding to Mr McBride's e-mail and was considering resigning from his role running LabourList, a Labour-supporting website.
On Wednesday, in an e-mail to members of Labour's National Executive Committee, the party's general secretary, Ray Collins, said Mr Draper - who had offered "advice and opinion on an ad hoc basis" - would not be asked for either again.
Mr McBride's actions were a "clear and serious breach" of Whitehall rules, the head of the civil service, Sir Gus O'Donnell has said.
But the Conservatives have written to Sir Gus demanding answers to a string of questions about who knew what about the e-mails.
They have also questioned the role in the affair of Cabinet Office minister Tom Watson, who has issued a statement through lawyers saying he had "no involvement in or knowledge of" proposals to set up Red Rag.
And the Scottish National Party has said International Development Secretary Douglas Alexander also faces questions about whether he knew of the plan, pointing to a 2008 article in PR Week magazine suggesting Mr Alexander was a key player in the Labour's "blog council" and had attended a meeting chaired by Mr Draper.
SNP Scotland Office spokesman Angus McNeil said: "It seems Derek Draper's poisonous blogging plans were not only discussed with Downing Street advisors, but at least one minister as well.
"Douglas Alexander has serious questions to answer on his role in this scandal."
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