Anger at false claim that tyrant's son was in captivity

The National Security Council met to discuss the reappearance of Saif al-Islam, whowas supposedly captured

British ministers expressed concern yesterday after Muammar Gaddafi's son Saif al-Islam defied claims that he had been captured by speaking to Western media in a Tripoli hotel.

The propaganda coup for the Gaddafi regime was discussed by the Government's National Security Council, which was chaired by the Deputy Prime Minister Nick Clegg after David Cameron returned to join his family on holiday in Cornwall.

There was alarm in Government circles that the International Criminal Court (ICC) appeared to endorse claims by anti-Gaddafi forces on Monday that the Libyan dictator's favoured successor had been captured. Talks were said to be under way about handing him over to The Hague to face trial.

One Government source admitted that Saif's appearance at the Rixos Hotel was a blow. "It wasn't what we were expecting. But these things happen in the fog of war and there will be setbacks and surprises along the way," he said. British officials do not believe that Saif escaped after being captured. They suspect there was a "miscommunication" between rebel fighters on the ground in Tripoli and their leaders that he was being held.

Sir Menzies Campbell, the former Liberal Democrat leader, criticised the ICC, saying its credibility had been undermined. He said: "I think we're likely to find more instances of misinformation of the kind that has just been exposed. It doesn't say very much, I'm afraid... for the credibility of that organisation that it should apparently have endorsed the information."

Mr Clegg insisted that Saif's media appearance gave a misleading impression because he was free to move around in only a limited part of Tripoli.

"This is not the sound of some great comeback from Gaddafi's regime. He is not roaming freely through Tripoli: he and the remaining pro-Gaddafi forces are cornered," Mr Clegg said. "It is only matter of time before they are finally defeated and Libya is completely free."

Mr Clegg defended Mr Cameron's decision to return to his holiday, saying: "He is in constant contact with other world leaders and leaders of the Transitional National Council in Libya."

Speaking last night, the Libyan rebel leader Mahmoud Jibril dismissed accusations against the Transitional National Council (TNC) over the reported arrest of Saif. He said a group of people posing as revolutionaries said they detained the Libyan leader's son, and his capture was not confirmed by the TNC.

He called Saif's appearance in Tripoli a desperate last-minute plea and a "cinematic show". Despite the reports of Saif's arrest being false, Mr Jibril said the episode had nonetheless benefited the rebels. "Word of his capture had given us a big military and political advantage. Many soldiers surrendered to the rebels," he said.

The ICC said yesterday it had never received official confirmation from the Libyan rebels that Saif had been captured. "There was no official confirmation from the Transitional National Council," said the ICC official Fadi el-Abdallah. "Different answers were given. That was a little ambiguous."

William Hague, the Foreign Secretary, insisted that the world was now witnessing "the death throes of the Gaddafi regime". But he warned: "There are many weapons out there, former soldiers, current Libyan soldiers, mercenaries who have been in the pay of Gaddafi... there may be some formidable problems ahead."

Mr Hague said the ideal outcome was for Col Gaddafi to answer the ICC indictment. "But it is up to the people of Libya and what happens politically," Mr Hague said. "The settlement they come to is up to them and that includes what happens to Col Gaddafi."