Britain and France have agreed on further nuclear cooperation but will retain their own independent deterrents, Prime Minister Gordon Brown said Friday, according to dpa. "We have agreed a degree of co-operation that is, I think, greater than we have had previously but we will retain, as will France, our independent nuclear deterrent," Brown told foreign journalists at a news conference in London. Brown and French President Nicolas Sarkozy held talks in London last Friday. But Brown refused to be drawn on a report in Friday's Guardian newspaper that the two countries would go as far as sharing patrols of their nuclear fleets. While not referring to submarines explicitly, Brown repeatedly stressed the importance for Britain of maintaining its independent nuclear deterrent. The idea of "shared deterrence" would go down badly in Britain at a time when the country is heading for a general election, analysts said. The estimated cost of 100 billion pounds (150 billion dollars) of modernizing Britain's submarine-based Trident nuclear missile system is currently hotly debated in Britain, and within the ruling Labour Party. Brown has previously said that he would be prepared to cut the number of submarines from four to three as a "gesture towards disarmament." France also maintains a four-submarine Strategic Ocean Force. "We wish, of course, to see multilateral disarmament around the world and we are ready to contribute towards that, but in a world that is so insecure, particularly with other countries trying to acquire nuclear weapons, we do not see the case for us withdrawing the independent nuclear deterrent that we have," said Brown. The Guardian reported that France had offered a "joint UK-French nuclear deterrent" by sharing submarine patrols.