Fiat SpA already controls 25 percent of Chrysler, Detroit’s third largest automaker.

Marchionne said only a few details need to be worked out and that “it’s a matter of days” before they’re sorted, according to the ANSA and LaPresse news agencies.

Marchionne said the increase might be finalized as early as Tuesday, according to ANSA. He was speaking during the presentation of Jeep vehicles near Turin.

Fiat took a 20 percent share in Chrysler in 2009, gaining effective control after Chrysler emerged from bankruptcy.

In exchange, Chrysler got small-car and clean-engine technology and Fiat’s management know-how.

The Italian company increased its stake to 25 percent this year, and Marchionne has said he expects to raise it to 35 percent by the end of 2011.