(CNN) Burning tires, tear gas and clashes with riot police -- the ugly scenes that come with workers' strikes are all too familiar in France, a country constantly trying to balance its culture of workers' rights with a more efficient economy.
Such scenes are being played out across the country Friday as unions have called for workers to step up protests that have for the past week crippled parts of France. Employees of oil refineries, nuclear power plants and some public transportation have left one in three gas stations dry, forcing vehicles to search for well-stocked stations and causing long lines at the pump.
People are now hoarding gas, worried that it may be some time until supply levels are back to normal.
The workers are protesting a labor reform bill put forward by the government that will make it easier for companies to hire and fire employees. The government's argument is that the strict laws that make French workers among the best protected in the world leave companies in a difficult position where they can't take on new staff.
It's part of the reason the country has an unemployment rate of more than 10% and young people struggle to get a foot in the market, the government says.
French Prime Minister Manuel Valls told local media on Thursday that he might be willing to modify some of the proposals, giving hope to French people that the protests and fuel shortages may soon stop.
But workers' unions Friday responded with a call to step up rallies and blockades, demanding a complete withdrawal of the bill.
We "call for the continuation and intensification of protests," a group of unions behind the protests said in a statement.
"The government's violent words, its contempt for the social movement and its refusal to withdraw this bill reinforces our commitment," it said.
CNN Senior International Correspondent Jim Bittermann, reporting from a gas station in Paris, said cars were waiting around half an hour to refuel.
"It is causing a lot of grievance for a lot of people," he said.
The strike is essentially a standoff between one large union, the CGT, and the government. The CGT was historically a communist syndicate but cut its links to the country's communist party in the 1990s and has taken a more moderate stance.
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In the western French city of Donges, protestors burned tires and trash in one of many blockades that have stopped fuel tankers in their tracks, forcing them to turn around or reroute.
"This week, the actions, the strikes and the blockades by workers from a number of industries to demand the retraction of this labor bill and to obtain new rights shows that our determination remains intact," several unions led by the CGT said earlier in an open letter.
They are particularly angry that the government is enacting a constitutional power to bypass parliament to pass the bill, which revises the country's current laws on working hours and layoff protections.
Current law limits French workers to 35 hours a week. If they work a few hours over, they are supposed to be compensated.
The 35-hour rule, which has been reformed many times, was originally put in place in 2000 as a way of encouraging companies to hire more people by limiting work hours.
Now the government wants to allow companies to ask staff to work up to 46 hours a week, or 60 in exceptional circumstances. Employers must give staff the extra time back, so that workers still average 35 hours a week over a three-month period.
The law also says that French workers must have 11 consecutive hours between shifts, but the government is proposing that this period could be broken up.
Current law makes it illegal for a company to lay off a worker if it is profitable. But the government is proposing that a company can fire an employee if its revenues have fallen for four consecutive quarters, even if it is still profitable.
The French government is getting ready to propose a new rule next month that would give workers the "right to disconnect" from their emails and smart phones when they're out of the office.
The French Petroleum Industries Union (UFIP) had earlier said that three of the country's eight refineries had shut down and that although supply was near sufficient, transporting gas to stations had been incredibly difficult. Other reports suggested more than three refineries were shut down.
The French government said around 30% of its 12,200 fuel stations were "in trouble," half of them completely dry.
It urged people not to panic, though fuel hoarding has continued.
"Indeed, in these last two days, the daily fuel consumption has been three times the usual amount, as people fear a possible shortage. We don't have a stock problem, we have a delivery problem," the government said in a statement.
It said it was trying to increase supplies at gas stations by freeing tankers that had been trapped in blockades and increasing the number of trucks.
Drivers delivering gas supplies to stations have been asked to work an extra two hours a day to ensure better supply, the government said -- an ironic measure to address a problem caused by workers refusing to work longer days.
The protests add to France's security woes as it prepares to host the Euro 2016 football championships next month, and the nation is still in a state of emergency following the deadly Paris terror attacks in November that left more than 130 people dead.