British police received a bomb threat for London from dissident Irish republicans Monday, on the eve of a historic trip by Queen Elizabeth II to Ireland.

The warning heightened tensions after a spike in violence in Northern Ireland and a statement by a top paramilitary group that the British monarch was wanted for "war crimes."

Britain summoned Syria’s ambassador Friday in coordination with other EU nations to warn of fresh sanctions against the regime if it fails to stop a crackdown on protesters, as Turkey's premier said it was premature to say whether President Bashar al-Assad should quit.

In a statement, the Foreign Office said it had "called in the Syrian Ambassador Dr. Sami Khiyami ... to express the UK’s strong concerns about the ongoing situation in Syria."

British police said Tuesday they had arrested five men under anti-terrorism legislation close to a nuclear plant in northwest England.

The men were stopped in a vehicle by officers near the Sellafield nuclear site in Cumbria at around 4:30 pm (1530 GMT) on Monday.

Britain expelled the Libyan ambassador Sunday following attacks on the British and Italian embassies in Tripoli, saying Moammar Gadhafi's regime had failed in its duty to protect diplomatic missions.

Protesters set fire to the buildings, which are on the same street in central Tripoli, early on Sunday, Agence France Presse reported, adding that the mob at the Italian embassy ripped down the Italian flag and threw it into the street.

Turkey is against foreign intervention in Syria and believes the unrest-hit country should solve its own problems, Anatolia news agency quoted Foreign Minister Ahmet Davutoglu as saying on Sunday.

"We should work to prevent the possibility (of a military intervention in Syria). Foreign intervention in a country like Syria with a heterogeneous social structure might cause unwanted consequences," Davutoglu said.

Prince William and Kate Middleton have decided not to leave for their honeymoon immediately and the newlyweds will stay in Britain this weekend, palace officials said Saturday.

William, who married Middleton on Friday in an opulent ceremony at Westminster Abbey, plans to return to military duty as a Royal Air Force helicopter rescue pilot in Wales at the end of this weekend, which includes a Monday holiday, officials said.

International Space Station astronauts sent greetings from the cosmos to Prince William and Kate Middleton after soaring over Britain on the eve of the royal wedding Friday.

In a message read by Paolo Nespoli, Ron Garan and Cady Coleman, the astronauts said they would be joining the estimated two billion earth-bound viewers of the royal nuptials, a third of the planet's population.

Malawi has declared Britain's top diplomat to the southern African nation persona non grata after his criticism of the president was leaked to the press, diplomats said Wednesday.

"I am sorry to pass on the news that the Malawi Government has officially informed the Foreign and Commonwealth Office today (Tuesday) that Fergus (Cochrane-Dyet) is being declared persona non grata," British high commission vice-consul Lindsay McConaghy wrote in a memo, a copy of which was seen by Agence France Presse.

Britain on Wednesday urged its nationals to leave Syria amid escalating unrest in the country against the regime of President Bashar al-Assad.

The Foreign Office said Britons should leave the country on commercial flights while airports remained open.

A rebel official in Libya's besieged city of Misrata pleaded for Britain and France to send troops to help fight Moammer Gadhafi's forces, while a son of the strongman said he was "very optimistic" his father's regime will prevail, sources told the Agence French Presse on Wednesday.

A senior member of Misrata's governing council, Nuri Abdullah Abdullati, said they were asking for the troops on the basis of "humanitarian" principles, in the first request by insurgents for boots on the ground.