Questions are being asked across the Libyan capital about the leadership of Colonel Gaddafi, who has not been seen since he reportedly escaped the air strike 10 days ago in which his son was killed.

Libyan officials at the time confirmed that Gaddafi had been in the home of Saif al-Arab, when at least two bombs dropped by Nato jets hit the family compound.

Fighter planes returned to the skies over Tripoli on Monday night for the first time since that attack, hitting six targets in the early hours and hammering home to a tired city that the eight-weekcampaign has not run out of targets.

On the streets of the capital that he has ruled for almost 42 years, Gaddafi's supporters were wondering aloud about their leader's fate, while at the same time complaining that the UN-imposed siege was taking an increasingly heavy toll.

"Yes it's true that his absence is strange," said one man in an inner-city coffee shop. He was not at his son's funeral and I thought he would be."

Gaddafi's absence from the funerals of Saif al-Arab, and his three grandchildren who were also reportedly killed in the attack, was blamed on security fears, with government officials insisting that the strike on his son's home had been an assassination attempt on the leader himself.

"It's obvious that they tried to kill him and I imagine his security people have told him to keep a low profile," said one senior Libyan official. "But it is strange that he has stayed silent since."

Gaddafi has made speeches at regular intervals over the past three months and has used the occasional public appearance, often at the gates of an ancient fort on Tripoli's Green Square, to rally support.

The messages had come to be seen as morale boosters for loyalists in the west of the country and for an army that is engaged in a bitter fight with rebel forces in central and eastern Libya.

With many government buildings destroyed and no sign of an end to the bombing, officials over the past week have put forward alternative figures to speak on behalf of the regime .

Libya's prime minister, Al-Baghdadi Ali al-Mahmoudi, spoke last week and said he would be addressing the international media weekly from now on. Tribal chiefs have also been given a more prominent role. A national conference of members from 850 tribes from all parts of Libya was held in Tripoli last week. As a result, tribal chiefs have been given more authority to arbitrate national disputes.

Mahmoudi denied there was anything odd in Colonel Gaddafi's low profile. "He has lost a son and he is mourning," he said. "He will be back with us soon."

Another official denied speculation that the 69-year-old Gaddafi had been wounded in the strike that killed Saif al-Arab. At least one European diplomat agreed. "Our understanding is that he is still about and that he is very upset about the death of his son," he said yesterday.

Whatever the reality, Gaddafi loyalists are becoming conditioned to a future without their leader solely commandeering centre stage. "Libya has to change and everyone knows this," said the senior Libyan official. "If reforms were announced when the people demanded them, we would not have been betrayed by the Arab League and by Europe and we would not be in this mess. It is a stalemate and something has to give. It has already changed actually, but no-one can admit that yet."