"It will take a bit more time" to complete the talks, SheikhAbdullah bin Zayed al-Nahayan told AFP ahead of French PresidentNicolas Sarkozy's visit to the Gulf state for talks on bilateralmilitary ties.
A deal would be a major boost for the plane's maker Dassault Aviation, which has yet to sell any Rafales for export.
A Dassault spokesman told AFP on Saturday that "a deal is unlikely in the next few days."
The UAE said in June 2008 that it was "seriously" considering replacing its fleet of 60 Mirage 2000 combat planes with Rafale.
Asked about progress in the talks, Sheikh Abdullah said on thesidelines of the conference that the private sector "would also beinvolved", in reference to Dassault.
Kouchner said he is "not in charge of the matter", while Sarkozy's Elysee office recently said that "there was progress".
Dassault previously held talks with Saudi Arabia, the largest Arab economy, on a possible deal, but the world's top oil exporter eventually opted to buy Eurofighter jets from Britain.
Dassault is also expected to re-enter a race to win a12-billion-dollar fighter plane deal in India after it was disqualifiedfor failure to meet technical requirements.
France is a leading military supplier to the UAE, which bought more than 400 Leclerc tanks from French firm GIAT in 1994.
Sarkozy was due to arrive in the capital later on Monday to inaugurate a French military base, the first in the region, as part of a 1995 defence pact that binds the two countries.