The threat of terrorist action in the US could result in the temporary closure of some of the country's most high-profile tourist sites.

The Statue of Liberty, the Washington Monument, the White House, the St Louis Gateway Arch and Philadelphia's Liberty Bell pavilion were all closed immediately after the September 11 attack.

However, Dave Barna, speaking for the National Parks Service, said that all the above attractions had new airport-type security measures put in place after the World Trade Centre tragedy and they would only be closed in the face of a specific threat.

Barna said: 'The parks are a place for a renewal of the spirit and that's why it's especially important for them to be open in times of national crisis. We'll fight hard to see that they remain open.'

'The outbreak of war would not in itself be cause for visitor access to be restricted to these or any other National Park site.'

The National Parks Service administers 388 locations throughout the US and welcomed 279,000,000 visitors in 2002. Details: www.nps.gov