By Ian Dunt Follow @IanDunt
The prospect of British intervention in Libya securing regime change seemed tantalisingly close today, as fighting broke out in the capital.
News reports indicated that Triploi was encircled by rebel forces to the west, south and east, while some parts of the city – particularly in the east – had reportedly seen inhabitants take up arms against the regime.
Nato air strikes have been supporting the rebel advance, which was said to have reached the western point of the capital at one point only to be pushed back by gunfire.
"The zero hour has started. The rebels in Tripoli have risen up," said Abdel Hafiz Ghoga, vice-chairman of the National Transitional Council (NTC).
"There is co-ordination with the rebels in Tripoli. This was a pre-set plan. They've been preparing for a while. There's coordination with the rebels approaching from the east, west and south."
As expectations rose that there might finally be a change of leadership in the country, shadow foreign secretary Douglas Alexander warned the government not to repeat the mistakes of Iraq.
"You need to be able to provide security immediately after a change takes place," he told the BBC.
"There's a heavy responsibility on the British government to make sure in these times the right action is being taken to prepare for every scenario."
Mr Alexander said that when he asked about the post-operation scenario in the Commons he discovered no Foreign Office or Ministry of Defence staff had been dedicated to it.
"I'm not confident," he said. "I have real concerns."
The British government is ensuring that any Britons left in Tripoli leave immediately.
Junior Foreign Office minister Alistair Burt said it had become impossible to negotiate with the Gaddafi regime.
"It has been clear that Gaddafi does not have a firm grip on reality and has not been interested in leading or negotiating," he said.
But Libyan information minister Moussa Ibrahim stressed the regime was open to talks and warned there would be massacres if the rebels took over.
"Tripoli is well protected and we have thousands upon thousands of professional soldiers who are ready to protect this city from any invasion," he said.
"We hold Mr Obama, Mr Cameron and Mr Sarkozy morally responsible for every unnecessary death that takes place in this country."
The conflict came as rebel forces expanded out from the strategic coastal city of Zawiyah, just 50 km west of Tripoli and a crucial source of oil.
With western links blocked and ties to Gaddafi's home town of Sirte cut off to the east, the dictator seems to be running out of options, but western capitals were still being circumspect this morning.
"There's a lot of support for Gaddafi in Tripoli and a lot of it is armed, manning road blocks," Sir Menzies Campbell said.
"My sense is he won't go without a fight. He won't go without pulling the temples down around him."
The former Liberal Democrat leader played down the role of the rebel army and suggested the bouts of fighting came from disaffected individuals within the capital.
"I don’t think this is the rebels advancing to gate of Tripoli," he said.
"I think this is the dissidents in Tripoli who, having seen recent events, have been emboldened about making a practical demonstration."
Former Libyan prime minister Abdessalam Jalloud, who defected from the regime in a dramatic move this weekend, called on Colonel Gaddafi's tribe to reject the leader.
"You are an honourable tribe," he said, taking to the air at Arabic news channel Al Jazeera.
"You should preserve your history and honour.
"'Disown this tyrant because he will go and you will end up inheriting his legacy."