The controversy over Gordon Brown's late arrival for an EU treaty signing ceremony has been dismissed by Downing Street as a "fuss over nothing".
Mr Brown signed the treaty after the other leaders
Mr Brown signed the EU reform treaty three hours later than 26 other EU leaders and missed an official ceremony and group photograph.
He was attacked by the Tories for "sulky rudeness" and the Lib Dems for "inept and peevish behaviour".
No 10 said: "He signed the treaty. It was in public. What's the issue?"
Asked repeatedly about Mr Brown's late arrival in Lisbon on Thursday, the prime minister's official spokesman said it was all a "fuss about nothing" that "did not matter to the average person."
The EU Reform Treaty, designed to replace the failed EU Constitution which was rejected by French and Dutch voters in 2005, is expected to greatly alter the way the 27-nation EU operates.
It has proved controversial in Britain where critics have demanded there should be a referendum and say it will transfer too many rights to Europe.
KEY LISBON TREATY REFORMS
Creates new European Council president
New foreign policy supremo to increase EU profile
Commissioners reduced from 27 to 18
Removes national vetoes in around 50 policy areas
Voting weights between member states redistributed
No reference to EU symbols such as the flag and anthem
Treaty faces referendum in Ireland and must be ratified by all other EU parliaments
The government says any changes are either minor and procedural or are in British interests and insists it has "opt-outs" on any that are not.
But the Sun newspaper accused Mr Brown and Foreign Secretary David Miliband of an "EU surrender" while the Daily Express accused him of a "cynical betrayal".
The Daily Telegraph accused the prime minister of "an embarrassing period of dithering" over attending the ceremony and the Guardian said his handling of the matter had been "cackhanded".
Mr Brown blamed his late arrival on having to attend a meeting of the Commons liaison committee at Westminster that morning, which critics say could easily have been re-arranged.
Mr Miliband attended the official ceremony in his place.
Shadow foreign secretary William Hague said Mr Brown's "sulky rudeness means that he has actually managed to lose influence in Brussels".
Mr Hague repeated his call for a referendum on the treaty, saying the prime minister had no "democratic right" to sign it without giving the British people a say.
Chris Huhne, for the Lib Dems, said Mr Brown was guilty of "inept and peevish behaviour".
On Friday Mr Brown arrived for his first Brussels EU summit since becoming prime minister, where leaders agreed measures to try to avert a crisis when Kosovo declares independence from Serbia.
On his arrival he told reporters that on Thursday, EU leaders had signed an amending treaty, and now they were starting a "different chapter" and looking at the economic, environmental and security challenges ahead.
EU Trade Commissioner Peter Mandelson, a key ally of former prime minister Tony Blair, earlier suggested Mr Brown should make the case for the EU more positively.
He told BBC Two's The Daily Politics: "In politics you don't win an argument by putting yourself on the back foot. If you have a case you make it confidently, you present it with conviction."
Asked if Mr Brown was doing that with Europe, Mr Mandelson said: "I think Gordon Brown believes in it, I think he is capable of doing it, I think he's prepared to do it. No doubt it needs to assume a higher priority."