Fiat Chrysler chief executive Sergio Marchionne cancelled his appearance at the Paris motor show, a spokesperson told Reuters, without giving any details.

Marchionne, also CEO and chairman of show draw brand Ferrari, was to have met with journalists on Thursday.

"The media availability with Sergio Marchionne on 29 September at the Paris Motor Show has been cancelled," FCA said in a statement. A spokesperson later told Reuters Marchionne would not be coming to the show at all.

A year ago, Marchionne canceled his appearance at the Frankfurt auto show after FCA was picked as the target company in labour talks in the United States.

It is possible Marchionne may be needed at the Unifor contract negotiations with FCA in Canada.

The union representing auto workers in Canada said last week that, pending ratification of a tentative agreement with General Motors, the next company in negotiations with the Detroit Three automakers would be FCA.

The deal with GM was ratified on Sunday.

National president Jerry Dias said: "Unifor will be seeking a pattern settlement that includes our top priority - investment."

Fiat Chrysler employs 9,750 Unifor members making the Chrysler 300, Dodge Challenger and Dodge Charger (Brampton Assembly Plant with 3,300 Unifor members), the Dodge Caravan and Chrysler Pacifica (Windsor Assembly Plant with 6,000 Unifor members) and cast components (Etobicoke Casting plant with 450 Unifor members).

Unifor secured more production for GM's threatened Oshawa assembly plant and the move of some engine/transmission production back to St Catharines in return for pension concessions for new recruits.

"We have one simple message for all the Detroit Three automakers: there will be no deal without commitments to new investments in Canada," Dias said before the GM ratification.