Fiat is not ruling out closing one of its Italian plants unless it can secure extra work to the US coupled with union agreement.

The automaker has witnessed challenging sales in Europe, but has floated the idea of supplying at near-capacity US sister company, Chrysler, with product from Italy.

However, should the concept not curry favour with Fiat's myriad labour bodies, the manufacturer concedes over-capacity could see it shutter one site in Italy.

"Given the under-utilisation of our plants in Italy [and] in an effort to resolve that issue, the company has [been] talking with Chrysler to see if we in Italy could build Chrysler or build products for export back to the States," a Fiat spokesman in Turin told just-auto.

"Chrysler is doing well and they are close to saturation point in the majority of sites we have in the US. In order to have that [US export] we have to have the unions on board - if we can't make this work... then there is one plant too many [in] Italy."

Fiat is at pains to point out however it is not a "brutal, I need to close a plant," view, but rather a way to address a depressed European market and in particular to make its sites work more efficiently.

"If we need to tick all these boxes, then yes, we have one plant too many," said the Fiat spokesman.

"We are at the beginning of this process - the first thing is to identify what product would need to be built for export."

Fiat secured agreement earlier this year with the majority of its labour bodies for enhanced packages dependent on improved flexibility - although the hard-line FIOM labour body refused to ink the deal.

"The other unions have signed, but it is FIOM that appears to be more of a political party than a trade union," said the Fiat spokesman.

"It is a bit tiring really - they have a stock response to anything and everything and obviously the political climate has changed in Italy with [new Prime Minister] Mario Monti."

FIOM was not immediately available for comment.