French President Jacques Chirac has said sending 15,000 peacekeeping troops to southern Lebanon is "excessive".
France already leads Unifil, the existing peace force
He was speaking ahead of Brussels talks on the Lebanon peace force, which France will lead, between EU ministers and UN Secretary General Kofi Annan.
At that meeting French Foreign Minister Philippe Douste-Blazy said EU nations have offered to send a minimum of 6,500 to 7,000 ground troops to Lebanon.
The force was authorised as part of the ceasefire between Israel and Hezbollah.
Speaking in Brussels, Mr Annan said that the plan would only work if the enlarged UN force, called Unifil 2, was "strong, credible and robust".
Mr Annan added that the first troops would deploy within days, not weeks.
The discussions in Brussels come a day after France pledged 2,000 soldiers and offered to command the expanded United Nations force.
But Mr Chirac, giving a joint news conference with German Chancellor Angela Merkel, told reporters: "I don't know who mentioned this figure but it doesn't really make sense.
UN TROOP PLEDGES
France - leadership and 2,000 troops
Italy - 2,000 - 3,000 troops
Bangladesh - two battalions (up to 2,000 troops)
Malaysia - one battalion
Spain - one mechanised battalion
Indonesia - one battalion, an engineering company
Nepal - one battalion
Denmark - at least two ships
Finland - 250 troops
Belgium - 302 troops, later rising to 392
Germany - maritime and border patrols but no combat troops
Norway - 100 soldiers
"So what is the right number, 4,000, 5,000 or 6,000? I don't know."
On Friday morning, a contingent of 170 French troops - specialists in demining and reconstruction - arrived on an amphibious assault craft at the southern Lebanese port of Naqoura.
The longer it takes to send in a more robust international force, the greater the chance that fighting could resume, says the BBC's Chris Morris, in Beirut.
Israel has reiterated that it will not finally withdraw from southern Lebanon until the UN peacekeeping force is deployed.
With Hezbollah still firmly established across the border region and in no mood to give up its weapons, there is some scepticism about what an international force can achieve however tough its mandate, he says.
And among Lebanese civilians in the south returning to houses damaged or destroyed, scepticism is mixed with resentment that it took the international community so long to bring the conflict to an end, our correspondent adds.
Mr Annan is in Brussels at the start of a diplomatic tour which will see him visiting both Lebanon and Israel and other Middle Eastern states, possibly including Iran and Syria.
Announcing France's final troop contribution on Thursday, Mr Chirac said his country had obtained the "necessary clarifications on the chain of command, which must be simple, coherent and reactive".
The UN was disappointed by the initial response of European nations to its calls for troops to enforce UN Security Council Resolution 1701 which ended the conflict.
France was criticised last week after offering just 200 extra troops to help bolster Unifil.
Welcoming news of France's fresh pledge, US President George W Bush said he encouraged other nations to make contributions.
The issue has been complicated by Israel's reluctance to accept troops from mainly Muslim states which do not have diplomatic relations with it.
Italy has promised 3,000 troops, while Spain, Greece, Finland, Latvia, Sweden and Poland are all believed to be considering a contribution.
However, Germany, the biggest EU nation, has ruled out sending combat troops as it is thought to be unwilling to enter a situation involving the Israeli military because of Germany's Nazi past.
In related developments:
- Russian Defence Minister Sergei Ivanov dismissed Israeli allegations that Hezbollah has been supplied with modern Russian weapons. Israeli officials have said they had proof that Russian anti-tank weapons delivered to the Syrian army had been passed on to Hezbollah
- An opinion poll in Israel has suggested that a majority of Israelis want Prime Minister Ehud Olmert to resign over the conduct of the conflict. The poll, carried out by the independent Dahaf Institute, showed 63% of Israelis saying Mr Olmert should go, and a majority saying they wanted the defence minister and the military chief of staff to resign.