PARIS/DOUCHY-LES-MINES (Reuters, AFP) - France has started using its strategic oil reserves to counter union blockades of its refineries, while police fired water cannon Wednesday (May 25) to disperse scores of activists blocking a north-eastern oil depot.

"Yes, a small quantity of the stock has been drawn. It was authorised by the government, only the government can authorise it," the French oil industry federation UFIP's spokeswoman Catherine Enck said on Wednesday.

Union Francaise des Industries Petrolieres (UFIP) President Francis Duseux told RMC radio that the industry had been using the strategic reserves for two days. "Every day we use the equivalent of about one day of consumption. At worst, if the situation remains very tense, we can do this for three months," he said.

In Douchy-les-Mines near the Belgian border, police fired water cannon to disperse scores of activists blocking a north-eastern oil depot, as pumps ran dry and unions stepped up strikes in a bitter battle over labour reforms.

With a fifth of petrol stations in France running low, police moved in to break a blockade that had been in place since Thursday.

"They cleared away all our barricades. The depot was unblocked without confrontation," said Willy Dans, a spokesman for the local branch of the SUD union.

"The police moved in quickly. They used water cannon. We got the feeling they were tense," Dans told AFP.

Watched by around 80 striking workers, firefighters extinguished burning tyres that were blocking roads and sending thick plumes of smoke billowing into the air.

Most petrol stations in the area were empty, forcing motorists to hop over the border to Belgium to fill up, reported an AFP photographer on the ground.

The blockades are part of a wave of social unrest that has seen thousands take to the streets in often violent protests against labour reforms proposed by President Francois Hollande's deeply unpopular Socialist government.

"We have to fight" against the reforms, said Dans, adding he felt the movement had popular support.

On Tuesday, Philippe Martinez, the leader of the CGT union which has mounted the blockades and strikes at refineries, vowed to continue the action until the labour legislation is withdrawn.

At least six out of the eight refineries in France have either stopped operating or have reduced their output due to strikes and blockades.

Transport was further hampered Wednesday by a rolling strike on the trains, causing chaos for commuters.

The social unrest has raised concerns for the smooth running of the month-long Euro 2016 football championships hosted by France which start on June 10.

"It's beginning to get to a critical point," said Pascal Barre, who runs a logistics firm in Poincy, east of Paris.

"We filled up at the end of last week and at the beginning of this week but our drivers need to fill up again and it's not possible."

He warned: "If we can't deliver to shops and supermarkets, it's going to put France on its knees."

Hollande has said the protests were unacceptable and has vowed to break the deadlock.

The blockades have sparked a dark warning from oil giant Total, which operates five of the refineries affected.

"If our colleagues want to take an industrial asset hostage for a cause that is foreign to the company, you have to ask whether that is where we should invest," Total CEO Patrick Pouyanne told reporters.

Martinez hit back on Wednesday, accusing Total of "blackmail." "As long as the government refuses to enter into discussion, there is a risk that the strikes will expand," the union boss warned on French TV.

Protesters are furious that the government rammed the controversial labour market reforms through parliament without a vote.

Opponents of the labour reforms say they are too pro-business and will do little to reduce France's jobless rate of around 10 per cent.

But an International Monetary Fund report has backed the government, arguing the reforms are needed to reduce unemployment.

FRANCE-POLITICS/OIL-RESERVES (URGENT)