"The departure of cigarettes in 2007 is not easy to replace," Patrick Faure said.
"They were were really paying a good part of the budget. I don't see easily one sponsor replacing them. But I think we can find two or three smaller sponsors who can share the kind of space they have on the car."
Faure said the team was now in talks with companies who had previously been unwilling to enter Formula One while cigarettes were present.
Japan Tobacco, owners of Mild Seven, confirmed in a statement that 2006 would be their final year in the sport after backing Benetton and then Renault since 1994.
Faure reported interest from new markets including China and India.
"We are in discussion with Chinese people, you have Indians coming, you have a lot of new countries where companies are big," he said.
"Basically, it's going to be very difficult to replace Mild Seven, but it's not impossible if we can show good results and accept...two or three (sponsors) replacing one."
