Self-employed private sector workers from across France, including lawyers, airline pilots, doctors and other health professionals have protested in Paris against the government’s pension changes.

The demonstration on Monday by workers in the professions libérales will pile more pressure on ministers as MPs meet to examine the proposed legislation.

A cross-party parliamentary committee will begin to examine each of the draft law’s 65 articles in detail on Monday afternoon. The bill is aimed at merging the country’s 42 separate pension schemes into a points-based “universal” system. The committee will also be faced with 22,000 amendments to the law lodged last week, 19,000 of them submitted by the hard-left La France Insoumise party, in an attempt to delay the legislation.

Until now, the most vociferous opposition to the changes has come from unions and public sector workers, particularly rail staff, whose six-week strike brought parts of France to a standstill.

The ramping up of opposition by self-employed workers, who staged mass protests in September last year and in January, means the government is facing a two-pronged assault against the pension changes.

Most of those marching in Paris were lawyers, many of whom have been on strike for three weeks, forcing courts and tribunals to postpone hearings.

“The image people have of a lawyer is someone who is affluent and doesn’t have financial difficulties and that is false,” said Jean-Philippe Labes, head of the Pau bar. “This is a profession that is getting poorer.”

Paris lawyer François Suberbere said the pension reforms were an existential threat to the legal profession in France.

“Our pensions are threatened. We are being told we have to pay more charges for fewer pension rights. This means many smaller firms that are vital to the legal system will not survive.”

Lawyers’ representatives had been due to meet the prime minister, Édouard Philippe, on Sunday, but the meeting was postponed.

While unions have taken industrial action and protested against the pension changes because they will lose existing rights and privileges, independent workers object to their autonomous pension schemes, which are in credit, being merged with other schemes that are in debt and a rise in their pension contributions.

Christiane Féral-Schuhl, the president of the National Bar Council, said in advance of Monday’s demonstration that it would be “historic”.

“Our status is independent; it’s neither that of the civil servants nor salaried staff. We have no guarantee of employment or social protection. We finance our contributions 100%. It’s not possible to mix this with other schemes … it would be like mixing cabbages and carrots,” Féral-Schuhl told Le Parisien.

The bill has been approved by the French cabinet. After it is examined by the parliamentary committee, made up of 70 MPs, it will be presented to the national assembly on 17 February for a first vote before being sent to the upper house, the senate. The government is aiming to have the bill passed before the summer recess and to roll out the new system on 1 December.

Richard Ferrand, the president of the national assembly and a member of Emmanuel Macron’s governing La République En Marche party, said the parliamentary commission had until next Friday to finish its work.

“If necessary, it will continue its work throughout next weekend. The obstruction will not work,” he said.