British Defence Secretary Liam Fox said a London summit between Prime Minister David Cameron and French President Nicolas Sarkozy would focus on joint training, cooperation on acquiring equipment and technology, making military equipment more compatible, and greater information-sharing.
Britain and France, both nuclear powers, have Western Europe's most capable armed forces. But both nations are cutting public spending to rein in big budget deficits, making it vital to get the best possible value in defence spending.
"This relationship will be taken to a new level - the closest it has ever been," Fox wrote in the Sunday Telegraph newspaper.
However, he said the initiative was not a repeat of a 1998 Anglo-French agreement seen as paving the way for a common European Union defence policy. "Nor is it a push for an EU army, which we oppose," he wrote.
Increased cooperation should allow both countries to continue to project force on the world stage by sharing sophisticated, but expensive, military capabilities.
About money
"This is about money," said defence analyst Charles Heyman. "The ways in which you can cooperate very, very quickly and save a lot of money are on things like air transport [and] pilot training. You can cooperate at sea. People are already doing it," he told Reuters.
Two weeks ago, Cameron's coalition government announced Britain's 36.9 billion pound ($59.20 billion) defence budget would be cut by 8% in real terms over the next four years as part of efforts to curb a record peacetime budget deficit.
Britain announced cuts to its army, navy and air forces. It pushed ahead with ordering two new aircraft carriers, although only one will be operational. Changes to the carrier's design mean it will be able to carry French or US planes.
French Defence Minister Herve Morin sketched out the extent of cooperation last week, saying France and Britain could station warplanes on each other's aircraft carriers and refuel each other's planes.
A British frigate could help protect French aircraft carrier Charles de Gaulle and vice versa, he said in an interview with French business daily La Tribune.
Other areas he cited were joint maintenance and staff training for the A400M military transport aircraft, joint work on a new drone or pilotless aircraft, and rationalisation of missiles.
Some reports say the two countries could coordinate to ensure that one of their aircraft carriers was always at sea.
Britain and France have also been discussing Britain's new fleet of Airbus refuelling planes, amid suggestions that France could sub-let some of the 14 planes.
The British and French finance, defence and foreign ministers will join Tuesday's talks, which are also expected to deal with Afghanistan, where both countries have troops deployed, and preparations for November's Group of 20 summit in South Korea.
(EurActiv with Reuters.)
