Italian labour leaders on Tuesday increased pressure on a local union to call off a strike at a Fiat car plant which has shut down virtually all of the company’s vehicle output in the country.

“We believe the blockages at Melfi must be removed,” Savino Pezzotta, national leader of the CISL union, said according to Reuters, which noted he was speaking on behalf of all three main national unions including the CGIL, a local unit of which is behind the strike.

The news agency said the strike, in its ninth day on Tuesday, erupted in clashes between police and demonstrators on Monday as worries grew that the blockage could threaten Fiat’s effort to recover from record losses and regain market share.

At issue in the dispute are the working hours at Melfi and lower wages for local workers compared with other Fiat plants, Reuters noted.

Analysts have said the strike could hurt Fiat if it continues for several weeks, the report said.

According to Reuters, a civil judge on Tuesday ordered the removal of the picket lines after Fiat asked for a court ruling. Although the judge does not have the authority to order police to remove the block, Fiat could use the order to seek damages from the unions.

The report said Melfi, in the southern Baslicata region, is Fiat’s most efficient plant in Italy and produces the popular Punto and the Lancia Ypsilon cars. It also cuts sheet metal for other Fiat factories in Italy and shortages of material from Melfi has caused 95% of the company’s carmaking in Italy to shut down.

Workers at Melfi are demanding that their conditions, from salaries to shifts, be brought up to the same levels as other Fiat factories and have rejected a schedule of negotiations accepted by three other union groups, Reuters added.

The report said some 500 workers blocked the plant entrance on Tuesday with about 400 police standing by after 10 demonstrators were injured the day before when police tried to clear the picket line with truncheons. Three police were also hurt by stones thrown by demonstrators at the plant in the poor region of Basilicata.

“We’re not rioters,” a 28-year-old worker, who gave his name as Dino, reportedly told a policeman. “We’re asking the company to sign an agreement with workers from Melfi but so far we’ve just met with a brick wall.”

Reuters said Fiat’s CEO on Monday wrote an open letter urging the strikers to return to the talks and warning of potentially dire consequences if they did not. So far, the dispute has cost Fiat the lost production of 16,300 vehicles, a spokesman told the news agency.