RAF jets and other Nato forces today struck a command and control centre where Libyan leader Colonel Muammar Gaddafi sometimes lives, it was announced.
The alliance said the dictator was not a target and there was no way of knowing whether he was there at the time of the raid.
His presence at the Bab Al Aziziyah complex was thought to be unlikely as he is reportedly staying in a different hospital every night in a bid to dodge the bombs.
Britain's Ministry of Defence said it could not comment on whether Gaddafi was believed to be there when the strikes were carried out.
RAF Typhoons were among Nato aircraft using precision guided weapons to bring down guard towers along the walls of the compound in the centre of Tripoli in the early hours.
The Chief of Defence Staff’s spokesman, Major General John Lorimer, said: “For decades, Colonel Gaddafi has hidden from the Libyan people behind these walls, spreading terror and crushing opposition.
“The massive compound has not just been his home but is also a major military barracks and headquarters and lies at the heart of his network of secret police and intelligence agencies...
“Last night’s action sends a powerful message to the regime’s leadership and to those involved in delivering Colonel Gaddafi’s attacks on civilians that they are no longer hidden away from the Libyan people behind high walls.”
Previous Nato attacks have hit command and control and other military facilities within the complex, he added.
The compound was badly damaged by US warplanes 25 years ago in response to a bombing that had killed two US servicemen at a German disco.
Today’s air strike came as Nato prepared to deploy attack helicopters over Libya for the first time.
With the international community trying to intensify pressure on Gaddafi to relinquish power, British Prime Minister David Cameron has confirmed that British Apache helicopters will join the latest offensive.
This comes amid intelligence reports that the dictator’s behaviour is becoming increasingly erratic.
And the Libyan regime was looking completely isolated on the world stage after Russia joined Western calls for Gaddafi to step down.
But there are concerns that the deployment of Apaches represents a further escalation of the conflict that could breach the terms of United Nations Security Council resolution 1973.
Russia, which has previously criticised the Nato air strikes in Libya, signed up to a G8 communique yesterday calling for Gaddafi to step down and offered to mediate his departure.