France will not meet the European Union's deficit target by 2015 as it had originally promised, as another black mark goes against the country's ailing economy.

Instead, French finance minister Michel Sapin said the country would need until 2017 to bring down the deficit in its public finances to the equivalent of 3% of GDP, the level agreed under the Maastricht Treaty.

Sapin said that in 2015, France would only cut its deficit to 4.3% of GDP because of weak growth and inflation in his country and across the eurozone, something he asked the EU to take into consideration. In 2014, the deficit will rise to 4.4%.

He added the French economy would grow by 0.4% in 2014 and 1% the following year.

France still has billions of euros more of austerity to wade through – mostly spending cuts – in order to get its public finances back on track.

Much of this will come from its sizeable social security budget, where funding cuts are politically difficult to make because it means reducing people's incomes.

This task has been made even harder by the unpopularity of President Francois Hollande, whose approval ratings have been the lowest of any French leader.

And those cuts mean French economic growth will remain sluggish for some time. They will likely depress household consumption and force unemployment up further in the country, which is already running at a rate of 10.2%.

A report by the Centre for Economics and Business Research (CEBR) said France is the biggest risk to the survival of the 18 member currency bloc.

"Whilst too much noise has been made about the PIIGS (Portugal, Italy, Ireland, Greece and Spain) and their slow progress in enacting reforms, there is also a French elephant in the eurozone room that no one dares to speak about," said Danae Kyriakopoulou, CEBR economist and main author of the report.

"Huge challenges lie ahead for France in terms of consolidating its public finances, improving damaged competitiveness and reducing high structural unemployment."

Kyriakopoulou warned there is "very little political capital in place to implement such reforms".

"The risk that the French economy will lag behind its neighbours in enacting reforms is not a trivial one," she said.

"While the troubles of the region's periphery have so far proven manageable, a crisis in the bloc's second-largest economy could have dramatic consequences for the viability of the currency union and push the eurozone to breaking point."