LONDON, JAN. 29 -- Britain and France agreed today to increase military cooperation, but talks at a one-day Anglo-French summit here failed to resolve deep differences over European Community spending.

In a news conference following a meeting this morning, Prime Minister Margaret Thatcher and President Francois Mitterrand outlined their common views on arms control, supporting the U.S.-Soviet Intermediate-range Nuclear Forces treaty, while insisting that the British and French independent nuclear arsenals be kept out of any arms talks in the forseeable future.

Both leaders reiterated their opposition to reductions in remaining short-range nuclear weapons systems in Western Europe.

Thatcher, who also met separately with French Prime Minister Jacques Chirac, spoke of the "steady advance of our cooperation on defense" and said that Britain still was considering the possibility of joint development of an air-launched nuclear missile.

British Defense Secretary George Younger said the two governments had agreed to allow port visits by each other's nuclear submarines and to hold joint maneuvers to test the possible use of French facilities to reinforce British troops on the Continent in times of crisis.

The summit cordiality appeared to contrast with remarks by Thatcher in an interview published today in France's L'Express magazine.

"Let's understand each other well," Thatcher said in response to a question about Anglo-French defense cooperation. "The defense of Western Europe is first of all NATO, and for this defense to remain effective, it is vital that American forces remain in Europe. This does not exclude numerous bilateral relations, but, and I insist on this point, within NATO."

France, while a member of the North Atlantic Treaty Organization, does not belong to the alliance's integrated military structure. Over the past year, however, Mitterrand has spoken increasingly of European cooperation on defense, and has moved toward a higher level of coordination with West Germany, as well as with Britain.

But in the interview, Thatcher dismissed the importance of a joint military brigade, which is the centerpiece of Franco-German cooperation. "What is the use of a Franco-German brigade?" she asked. "When France and Germany stage joint maneuvers they call them 'Bold Sparrow'; when we maneuver with the Germans, ours are called 'Lionheart,' " the name of a regular NATO exercise.

She was similarly dismissive of a possible Anglo-French brigade: "What could be done with such a brigade that would not be able to be done in the framework of NATO maneuvers? I do not believe in initiatives for the gallery. I am for effectiveness."

Asked today for comment on Thatcher's views, Mitterrand responded that "French policy is laid down in Paris. Policy in the Federal Republic of Germany is laid down in Bonn, not in London. Madame Thatcher has never expressed the desire to make decisions for her friends." Mitterrand said Thatcher was "very firm in her own conceptions," but she had addressed no questions to him on the subject.

Both leaders said they had failed to agree on the most contentious issue confronting a summit of European Community leaders scheduled for next month. France, Mitterrand said, sides with West Germany in calling for a compromise on farm spending that would encourage farmers to leave some land fallow.

Thatcher has pressed consistently for reduced spending on the Common Agricultural Policy, which consumes the bulk of the Community budget. The subsidy expended each year on one Community cow, she often points out, exceeds the annual per capita income of some underdeveloped countries.

"Our approaches are very different," Mitterrand said, "and no basis for agreement was noted today."

Washington Post Paris correspondent Edward Cody contributed to this article.