The aim of the discussions is to gain wider support for the Proliferation Security Initiative (PSI) launched in May by US President George W. Bush on the interception of shipments of WMD-related materials.

It includes agreement on the boarding of ships, forcing aircraft to land and the searching of cargoes.

Eleven governments signed up to the PSI principles last month at talks in Paris and the signatories are now looking for broader international support.

The group of 11 comprises Australia, Britain, France, Germany, Italy, Japan, the Netherlands, Poland, Portugal, Spain and the United States.

A Foreign Office spokesman said that about 50 countries had expressed interest in joining the organisation.

The spokesman added: "This is an important meeting. We strongly support the Proliferation Security Initiative and we hope that the meeting will allow us to make the initiative even more operational".

The three-day talks in London will include an exercise simulating the interception of a flight suspected of carrying WMD, paving the way for a live exercise later this year.

WAR.WIRE