Liberal Democrat ministers, MPs and activists rallied round Nick Clegg yesterday after his surprise mea culpa for his U-turn on university tuition fees – but his words failed to defuse anger among student leaders, who demanded a change of policy instead of a display of contrition.

The episode also took a bizarre turn when a spoof video setting the Deputy Prime Minister's solemn apology to music went viral on the internet, potentially exposing Mr Clegg to fresh ridicule over his decision in Government to tear up an election commitment to oppose higher fees.

The party released footage of his apology – to be screened next week – ahead of its annual conference in an effort to kill off the subject before delegates start arriving in Brighton tomorrow. Senior party figures lined up to back Mr Clegg's initiative, although Vince Cable, the Business Secretary, was careful to point out he had been sceptical about the election pledge.

Crucially for Mr Clegg, the MP Greg Mulholland, one of the most fierce Liberal Democrat critics of the fees about-turn, welcomed his apology. He said: "This took courage and I hope people give him credit for saying that publicly."

The majority of activists posting on the Liberal Democrat Voice website also supported their leader. Its co-editor, Mark Pack, said: "Overwhelmingly, party members have welcomed him taking a big and bold step on an issue that is clearly still a big and damaging problem for the party."

However, as the first undergraduates subject to the new funding system started arriving at university, the National Union of Students was scathing in its verdict. Its president, Liam Burns, said: "It's up to Nick Clegg now to reach out and apologise to those he betrayed by breaking his fees pledge and to make amends by changing his policies."

Liberal Democrat sources insisted there would be no alteration to Coalition policy on higher education funding, but did not rule out the party campaigning to abolish tuition fees at the next general election.

Nick Clegg has consented to the video mocking his apology to be released as a single on iTunes, with profits from sales going to the Sheffield Children's NHS Foundation Trust.