French workers threatened to shut down the country's nuclear power stations on Wednesday as it emerged that the state has been forced to delve into emergency petrol reserves for the past two days.

As the standoff continued between hardline unions and the ruling Socialists over a controversial labour reform, the majority of French blame the government for the tense standoff and will hold it accountable if the upcoming Euro 2016 football tournament "is a mess", a poll suggested on Wednesday.

The so-called El Khomri labour law (named after the French labour minister, Mariam El Khomri) aims to loosen France's notorious rigid labour market and reduce employee protection but in return create new jobs.

The idea is to close the huge gap in France between virtually unassailable permanent jobs and the precarious short term contracts lasting on average three months handed out in 90 per cent of new job deals.

The law is seen as the deeply unpopular President François Hollande's final attempt to reverse record unemployment - now around five million counting all categories - before next year's presidential elections.

However, many French, in particular those in state-run sectors, see it as an assault on hard-fought workers' rights. In the past two months, they have staged seven days of strikes and protests, some violent, plus a host of often-nightly rallies as part of a movement called "Nuit Debout", or Up all Night in Paris and other major cities.