Gordon Brown will urge Britain's Nato allies to boost their contributions in Afghanistan during crunch talks at a summit in Bucharest.
At a Nato summit in the Romanian capital, the Prime Minister and US president George Bush will call for more of its 26 members to commit troops or extra resources to the battle against the Taliban.
A special session of the summit has been set aside for the tough negotiations on the issue.
The Prime Minister told reporters travelling with him: "What I want is the process of burden-sharing to be more effective over the next period of time. We also believe there could be a greater burden sharing with countries providing equipment, even where this equipment will be used by the forces of other countries.
"We are setting up a Helicopter Trust Fund to enable countries to re-equip their helicopters, to get them ready for Afghanistan and train the pilots to use them."
Mr Brown will also seek clarification from French president Nicolas Sarkozy of his promise of 1,000 extra soldiers, provided certain conditions are met.
A Nato spokesman said on Wednesday night that Mr Sarkozy had offered hundreds of extra troops for the mission in Afghanistan.
The president has offered a battalion -- normally around 700-800 troops -- for the volatile eastern region of Afghanistan.
Mr Brown held informal talks with President Bush and United Nations secretary general Ban-Ki Moon on Wednesday night, before a working dinner with all his fellow leaders.
There may be more bitter wrangles with other alliance members who are still reluctant to share more of the military burden in Afghanistan, although Britain is keen to stress 40 countries already contribute in some way.
