The Bush administration said yesterday it would persevere with efforts to convince its partners of the merits of placing missile defence bases in Europe - in spite of this week's revelation that the US no longer believes Iran has a nuclear weapons programme.

Washington has said that the proposed European bases - missile interceptors in Poland and radar in the Czech Republic - are needed to guard against a threat from Tehran. But both Polish public opinion and the new Polish government have yet to be convinced hosting a missile defence base would benefit the country, while Russia has suggested that the programme is intended to counteract its own nuclear deterrent - a charge the US denies.