France is confident that it can sign and seal a firm $12 billion deal to supply India with 126 Rafale fighter jets "within six to nine months," government spokeswoman Valerie Pecresse said Wednesday.

The Rafale, a modern multi-role jet built by Dassault Aviation, has been selected by India as its preferred next generation interceptor, but details of the immense contract remain to be ironed out.

"It needs to be finalised but the French offer is the most competitive and that has been recognised by our partners," Pecresse said, after President Nicolas Sarkozy hailed the deal at a cabinet meeting.

Asked on BFM radio his estimate of the chances a final deal will be signed, Defence Minister Gerard Longuet said "in my opinion it is 80 percent."

The most optimistic forecasts were that the deal could be concluded within six to nine months, he added.

India announced Tuesday it had selected the French firm Dassault over the Eurofighter consortium for "exclusive negotiations" as the preferred bidder in a contract estimated to be worth $12 billion (9.1 billion euros).

If concluded, the contract would mark the first time the jet had found an export partner, despite being in service with the French military since 1998 and having proved itself in several conflicts.