Ports across the UK, including Southampton Docks, are on full alert after government warnings on a possible pre-Christmas attack by Al Qaeda terrorists.

Cross-Channel ferry ports, such as Portsmouth, have been especially earmarked for heightened security measures but all international maritime gateways have been told to be on guard.

Intelligence services warned European ferry operators that terrorists were planning to strike last weekend by planting a lorry bomb on a vessel.

This comes as Prime Minister Tony Blair revealed that "barely a day goes by without some new piece of intelligence coming via our security services about a threat to UK interests".

It is a matter of policy that security matters are not discussed by Associated British Ports, the owner and operator of Southampton Docks, and 20 other ports around the country, but the government has ordered increased vigilance against the present high risk of terrorist attacks.

Ferry ports are on the highest state of alert after French and Dutch intelligence services warned that a lorry loaded with explosives would attempt to board a cross-Channel vessel.

America's FBI is also thought to have passed on information to the government about a threat to a North Sea ferry.

Southampton's main port activities centre on global container traffic, cruise ships, vehicle imports and exports and bulk cargoes, although the docks do have a regular roll-on/roll-off link with the port of Santander in Spain, which began in May of this year.

Britain's transport security warning service, Transec, played the warning down in a secret bulletin to ports last Friday however at the same time all British ports with roll-on/roll-off ferry services were ordered to a level of alert described as "heightened emergency'' - the highest state they have been on since the current alert system was introduced.