Automaker Stellantis will once again halt car production at its historic Mirafiori plant in Italy, which makes the electric Fiat 500 and two Maserati models, a trade union source said on Friday, confirming press reports.

Auto production at the site, which had been suspended from mid-September until Nov 1 due to poor demand, resumed this week but is due to stop again for the whole of December, the source said, citing "inside information".

He said Stellantis had not yet officially communicated the move to unions - as is customary in such circumstances - but the new pause seemed inevitable given the information coming from suppliers and other sources.

Earlier, Italian MF daily said the Fiat 500 assembly line had reopened on Monday on a reduced output of 170 vehicles per day, and would close again for the whole of next month, "with a reopening after January 7".

Mirafiori, based in northwestern Turin, the hometown of the Fiat brand, is a massive industrial complex that is largely idle. The trade union source said the December stoppage would also involve its slow-selling Maserati sports cars.

MF said Stellantis had concentrated three months' worth of Fiat 500 orders into November production, and wanted but failed to also have some output in December due to supply problems leading to a shortage of components.

"This is a rumour that has no official confirmation. The company will verify in the coming weeks the production schedules for December," a spokesperson for Stellantis told Reuters when asked for comment on the newspaper's report.

The Turin head of the FIM-Cisl union, Rocco Cutri, told Reuters that his organisation had no certainties, but was nevertheless expecting Mirafiori workers to be furloughed again at the end of November "for at least two to three weeks".

Stellantis is facing industry-wide challenges such as low demand for more expensive electric vehicles and competition from China. It is also grappling with bloated U.S. inventories that have led it to cut profit and cash-flow forecasts.