By Andrew Parker, Political Correspondent Financial Times

Two UK government departments have clashed over whether Britain should co-operate with the US on its controversial plan to build a national anti-missile shield.

The rift has emerged in statements made by Geoff Hoon, defence secretary, and Peter Hain, the Foreign Office minister responsible for nuclear non-proliferation issues.

Mr Hoon, asked whether the UK would co-operate with the US if it went ahead with the shield, said Britain had a history of being "sympathetic" to requests for assistance by Washington.

But Mr Hain, echoing widespread concern in Europe about the anti-missile shield, said there was a "potential conflict of interest" between the defence system and the 1972 anti-ballistic missile treaty between the US and Russia.

European members of Nato are worried that if the US adopts the anti-missile shield it could fuel an arms race with Russia and China, without necessarily fulfilling its purpose of providing protection against rogue nuclear states such as North Korea.

Washington has raised with the Ministry of Defence the possibility of using a listening station at Fylingdales, Yorkshire, as a site for ground-based radars to detect attacks on the US as part of the shield.

Bill Clinton, US president, intends to decide in June whether to press ahead with the national missile defence system.

Mr Hoon, speaking on Channel 4 News, questioned whether the anti-missile shield would breach the 1972 treaty and intensify the arms race.

"This is a treaty between the US and Russia. The question of any kind of deployment in the UK breaching the treaty is not as clear cut as you suggest," he said.

Mr Hoon's comments have caused concern in the Foreign Office, which is worried that a row about the shield could undermine next month's non-proliferation treaty review conference in New York.

"No one wants to see the New York conference be dominated by a controversy over national missile defence," said Mr Hain.

Mr Hain was speaking at an event organised by the parliament's all-party group for non-proliferation and global security.

Michael Douglas, the US actor and UN goodwill ambassador on nuclear disarmament, also addressed the meeting and warned that the anti-missile shield could allow the world to slide into "nuclear anarchy" because Russia and China were opposed to it.

On Tuesday Mr Douglas met Robin Cook, the foreign secretary, and discussed the shield with him.