* Striking workers disrupt production at Aulnay plant
* Peugeot must finalise closure terms, restart production
* Move highlights growing state involvement
By Nicholas Vinocur
PARIS, Feb 14 (Reuters) - The French government named a mediator on Thursday to broker talks at Peugeot's Aulnay plant as tensions worsened between workers willing to accept terms of the carmaker's restructuring plan and unionists fighting against it.
Production has been near standstill at the factory north of Paris since the hardline CGT union and members of other unions called a strike three weeks ago to protest its planned closure in 2014 and cut 8,000 jobs across France.
The government's move to send a mediator into a private company highlights the breakdown in relations between staff and management at Aulnay, a 39-year-old plant known for being home to far-left unions.
Four unions excluding the CGT struck a deal with management this week to speed up transfers of some 1,500 staff to a nearby factory, citing a tense climate and attempts by strikers to intimidate non-striking employees.
But PSA Peugeot Citroen must still finalise details on the future of the plant's other 1,500 workers not concerned by transfers and restart production, which has been disrupted by the presence of striking workers on the factory floor.
Labour Minister Michel Sapin said that he had named a local official and chief labour inspector Marc Leray as a mediator to ease communication between Peugeot and the strikers.
"The situation at Aulnay-sous-Bois is characterised by worsening tensions. These no longer allow for a relaxed dialogue between all parties at the site," Sapin said in a statement.
The decision shows the growing involvement of President Francois Hollande's Socialist government in industrial disputes as it struggles to stop job losses in a string of plant shutdowns while spurring a return to economic competitiveness.
Tanja Sussest, head of the Aulnay chapter of moderate union SIA, which is not striking, denounced a "climate of terror" there and called for intervention by the police prefect of the Seine-Saint-Denis region to keep workers safe.
Strikers wielding wooden sticks resembling baseball bats had broken into a works council meeting on Tuesday attended by non-striking workers, she said in a statement. "A woman was so shocked that she suffered a severe breakdown," she said.
Tensions Aulnay and Peugeot's failure to maintain production contrast with the situation at rival and number 2 French carmaker Renault, which has obtained concessions from unions to boost productivity at several plants.
Both Peugeot, which announced record losses on Thursday , and Renault, which predicted an upturn in sales this year, must slash production capacity in a shrinking European market for their mid-range cars.
Ricardo Madeira, a representative of the CFDT union's Aulnay chapter, some of whose members have joined the strike, said he doubted the mediator would obtain results.
"As a union member, I don't think that the arrival of a mediator is going to save the world," he told BFM TV. "There have been 10 negotiating sessions and no progress." (Reporting By Nicholas Vinocur; Editing by Elaine Hardcastle)