Protesters scale Libyan embassy roof in Knightsbridge
Up to five protesters have gained access to the Libyan embassy building in Knightsbridge, central London.
Officers were alerted at 0250 GMT to reports of people having climbed on to the building's roof. The protesters have removed the embassy's green flag.
They have access to one of the rooms and officers are trying to "secure a safe resolution", police said.
Two other men, 25 and 26, who were trying to join the protesters on the roof have been arrested.
The men were arrested on suspicion of attempted trespass on diplomatic premises, a Metropolitan Police spokesman said.
Officers said the protesters who remained in the building had entered the room through the roof, but that they did not have access to the rest of the building.
The protesters removed a Libyan flag from the flagpole replacing the national flag with one used by Libyan rebels, police said.
The incident comes after what began in February as peaceful protests in Libya against Col Muammar Gaddafi's 42-year-long rule turned into fierce clashes between opposition groups and the regime's troops.
Britain, France and Lebanon are increasing the pressure for a no-fly zone over Libya to prevent air attacks on rebels by pro-Gaddafi forces.
The Arab League has also backed the idea, though some nations, said to include Germany, Russia and China, are opposing the proposals.
Earlier speaking to BBC London 94.9, a friend of the protesters, who did not want to be named, said the "peaceful protest" was aimed to coincide with the no-fly zone deliberations at the UN.
"The reason for their protest is to remind the world of the plight of the Libyan people.
"We are reminding them [politicians] that Libyan people want this no-fly zone immediately because they are being annihilated by a totalitarian regime in Libya."
He said the rooftop protesters had replaced the current regime's green flag with a flag from the pre-Gaddafi era.
Earlier this month a group calling itself "Topple The Tyrants" occupied a £10.9m house belonging to the Libyan leader in Hampstead Garden Suburb in north London.
After the protests in Libya turned violent, demonstrators gathered on the streets of London on 21 February.
During that rally a protester entered the Libyan embassy and replaced the regime's green flag.