France is on the verge of a “democratic breakdown”, Emmanuel Macron was warned last night after he rammed his unpopular pension reform through parliament without a vote.

The opposition said the move was a denial of democracy and an admission of weakness while unions warned it was tantamount to a declaration of war.

A demonstration of several thousand people erupted last night in Place de la Concorde in Paris, where police used tear gas and water cannon to disperse protesters.

To chants of La Marseillaise and “resign” from the opposition, Elisabeth Borne, the French prime minister, announced her minority government would trigger article 49.3 of the constitution that bypasses a vote.

In scenes of high tension, she declared: “We cannot gamble on the future of our pensions, and this reform is necessary.”

Mr Macron reportedly told ministers during an Elysee crisis meeting that the “financial risks” were too great not to see the reform passed.

France Unbowed, the hard-Left party, and Marine Le Pen’s Right-wing National Rally both said they would back a proposal by an independent centrist MP group to table a joint no-confidence motion. Should it pass, the prime minister will probably resign and Mr Macron could dissolve parliament.

Should it fail – the more likely outcome – opposition groups pledged to seek to overturn the reform by filing an appeal with the constitutional council or seeking a referendum, which requires the backing of a fifth of parliamentarians and a tenth of the voting population – 4.87 million people.

Mr Macron has staked his reformist mettle on passing the reform to raise the retirement age from 62 to 64 by 2030. The seemingly innocuous change, which the Macron camp insists is essential to avoid the pay-as-you-go system collapsing, has sparked a massive public and union backlash.

Two-thirds of the French have backed a string of massive strike protests since early January that have failed to sway government resolve.

The majority-Right Senate adopted the legislation yesterday morning, but a vote in the lower house National Assembly scheduled for the afternoon was so uncertain that Ms Borne chose to circumvent it.

“We cannot take the risk of seeing 175 hours of parliamentary debate collapse. We cannot take the risk of seeing the compromise built by the two Assemblies dismissed,” she told MPs.

The bill’s fate was in the hands of around 60 MPs from the opposition Republicans (LR) party, who were kingmakers.

However, dozens remained determined to oppose the reforms, although they practically mirror those that the Republicans have long called for.

Defeat for the government would have been a massive setback for Mr Macron, less than a year after he secured a second term as president.

He ran on a manifesto with a central pledge to raise the retirement age in order to keep the country’s generous social welfare model afloat.

Mr Macron let it be known on Wednesday night he would let the lower house of parliament vote on the text, but after crisis talks yesterday morning he changed his mind.

He reportedly told ministers that while his presidency was not on the line, “I consider that as things stand, the financial and economic risks are too great” to not push through the reform without a vote.

He added that democracy would be respected as a confidence vote would take place.

Aurelien Pradie, a renegade Republican, suggested the decision to bypass parliament signalled that France was on the verge of a “democratic breakdown”.