A single plant closure by each of General Motors and PSA - Bochum and Aulnay - "is not going to be enough for the current market situation", an analyst has said.

The likely shuttering of Aulnay and Bochum would be a "a step in the right direction", Barclays Capital analyst Michael Tyndall told Reuters.

Production at Peugeot's European car plants will fall to 75% of installed capacity this year from 84% in 2011, while GM car output drops to 72% of regional capacity from 84%, according to IHS Automotive forecasts cited by the news agency.

According to leaked Peugeot documents, executives decided early in 2010 to prepare for Aulnay's closure four years later - when the company's 10-year plan forecast 2.6m deliveries in a European auto market seen at 17.2m light vehicles.

The market and Peugeot's share of it have both worsened since.

Peugeot can now expect 2.06m European deliveries in 2014, based on Barclays Capital's 15.5m vehicle forecast and the automaker's 13.3% market share last year, the news agency said.

That is 540,000 vehicles below the company's medium-term forecast and 340,000 below the worst-case "stress test" scenario outlined in the same confidential presentation.

GM Europe said last week it would will concentrate assembly of its Astra compact in Britain and Poland from 2015 Production would stop at the brand's home plant in Ruesselsheim and increase in Ellesmere Port, England. Earlier this week, Opel chief Karl-Friedrich Stracke declined to give a workers meeting at Bochum assurances of the plant's future beyond 2014.

PSA want to halt production of its midsize Citroen C5 in Rennes, western France and build the next generation in a General Motors plant.

In return, Peugeot managers have told workers that Rennes may build another Astra-sized GM model such as the Zafira minivan. Annual French production of the four-year-old C5 model has dwindled to about 66,000.

But the Astra decision leaves GM with its own production hole to fill in Germany - making it unlikely that a significant number of compacts would be left over for Peugeot plants, Reuters noted.

The plant choice leaves more capacity to be filled - or closed - in Germany and France.

"It highlights their willingness to make tough decisions, even at the risk of more confrontation in their home markets," Tyndall said.

GM and Peugeot are braced for industrial unrest over planned factory cuts.

Peugeot had no comment to make on capacity decisions or the GM alliance plan, a spokesman told Reuters. GM also declined to comment.

GM has said annual production at Ellesmere Port can increase to as many as 200,000 Astras from the current 140,000.

Opel Ruesselsheim workers have won assurances from GM that their plant has a future within the group and unions now expect Zafira production to move to Ruesselsheim.

"The Astra decision worries us," Xavier Lellasseux, an official with Peugeot's centre-left CFDT union told Reuters. "All in all we're pretty sceptical about the alliance's impact on jobs."

GM's Opel division employs some 40,000 workers in Europe, of which 22,000 are in Germany. That compares with Peugeot's European workforce of 167,000, which is 60% French.