US tightens security

On guard: Security stepped up again at US airports

The US has moved to tighten security at key sites around the world and its own major cities in the immediate aftermath of its attacks on Afghanistan.

US Vice President Dick Cheney was moved from the White House to a secret location soon after military action against Afghanistan began.

Moved to safety: Vice-president Cheney

The US State Department has advised all Americans living or working abroad to take extra precautions in their personal security, and the FBI has placed police forces throughout the United States on maximum alert.

The US embassy in Saudi Arabia was also closed amid fears of a terrorist counter-attack.

Tightened security

Security precautions in the US have included closing off streets around the White House, preventing parking in front of government buildings and searching everyone who goes into high-profile buildings, including sites in New York and Washington.

In Los Angeles, the television industry's Emmy awards ceremony was cancelled, security tightened around electrical and water faciities and the highway patrol placed on 12-hour shifts in the event of a terrorist attack.

Additionally, the mayor of Baltimore said that major buildings and also mosques and synagogues were being placed under additional police guard, and Philadelphia has placed bomb squads on call and redeployed its police to guard major buildings.

The US coastguard has put 24-hour armed surveillance in 300 US ports, and National Guard troops were also being deployed for the first time in many airports across the country.

National Guard

New York has had the highest security in place for the last three weeks, with more than 4,500 armed National Guard soldiers on call and police officers drafted in from other cities.

Mayor Giuliani: No "lock down"

The city's mayor Rudy Giuliani said on Sunday extra security measures had been taken in the city, but there was no "lock down" of the city, as suggested in some reports.

"Life goes on as normal in New York," Giuliani told reporters.

"Yes we have heightened security; we've had that for some time. It has been increased as a result of the action that's being taken in Afghanistan."

Airports

He also thanked tourists - including those from the UK - who had continued to visit New York after the 11 September attacks.

"If we can maintain a steady way of life, we'll be a great example to the rest of the country and the rest of the world," he said.