Uncollected rubbish clogged streets in France's capital on Wednesday as unions made an eleventh-hour bid to stop a deeply unpopular pensions reform from being passed.

Opinion polls show that around two-thirds of French people are against the legislation to raise the retirement age from 62 to 64, extend contributions for a full pension and scrap some special privileges for public sector employees.

But despite two months of protests and cross-sector strikes, the bill championed by President Emmanuel Macron appears on the verge of being pushed through parliament.

Several small demonstrations kicked off around France on Wednesday morning, including in the northern city of Calais, in a new day of strikes and protests.

Police were expecting between 650,000 and 850,000 demonstrators nationwide, a source said on condition of anonymity, far fewer than the largest rallies last week.

Walkouts appeared more limited than in previous days of nationwide action, but workers in some sectors stood steadfast in rejecting the changes.

The most visible impact of the standoff so far has been piles of trash on Paris streets, where municipal garbage collectors and cleaners have stopped work since early last week.

Around 7,000 tonnes of black bin bags and cardboard boxes have accumulated on pavements and outside restaurants in around half the city, alarming foreign visitors.

Even in the other half of Paris, where private companies still whisk away refuse, collection has been complicated as two key incinerators outside the capital are on strike.

The street cleaners voted on Tuesday to extend their walkout until next Monday, causing Interior Minister Gerald Darmanin to demand the capital's municipality order them back to work.

Paris mayor Anne Hidalgo retorted she had "no power" and no intention of doing so.

"We won't have the same level of disturbances of public transport as during previous protest days," Transport Minister Clement Beaune meanwhile said earlier Tuesday.

The main suspense is whether Macron's minority government can muster the required number of votes in the lower parliament, where it will need the support of the opposition Republicans party (LR) in order to pass the legislation.

A joint vote from the lower National Assembly and the Senate could come as early as Thursday.

Minority government

In other sectors, several refineries across France were not delivering fuel on Wednesday, CGT union representative Eric Sellini said.

Public transport was to be "very disrupted" between Paris and the suburbs, but only slightly affected inside the city walls, the RATP operator said.

Nationwide, three out of five high-speed trains were running, the national railway operator SNCF said.

Power stations around the country had reduced output on Tuesday, power supplier EDF said, as energy workers feared losing their special privileges to the pensions reform.

But the last day of protests on Saturday saw a far lower turnout than in the previous rounds, while strikes last week did not paralyze the country as unions had hoped.

Macron's flagship proposal would raise the minimum retirement age from its current level of 62 to 64, bringing France more into line with its European Union neighbors, most of which have pushed back the retirement age to 65 or higher.

The law also hikes the requirements for a full pension and would abolish the retirement privileges enjoyed by some public-sector employees, such as those at the Paris Metro.

After initially claiming it was intended to make the system fairer, the government now emphasizes that it is about savings and avoiding deficits in the coming decades.

In a speech to deputies on Tuesday, Prime Minister Elisabeth Borne insisted that there was a majority in parliament for the changes, appealing to LR lawmakers who have long championed pension reform.

A vote in favor was "not support for the government," she said.

"A majority exists that is not scared of reforms, even unpopular ones, when they are necessary," Borne said.

Opinion polls show that around two-thirds of French people are against the legislation.

If Borne fails to find a workable majority in the lower house, she could use a constitutional power contained in article 49.3 of the constitution, enabling her to ram the legislation through without a vote.

Analysts say this would deprive her and Macron of democratic legitimacy in the face of hostile public opinion and would also expose the government to a confidence vote, which it might lose.

Political scientist Gilles Finchelstein, the head of the Jean-Jaures Foundation, a Paris-based think tank, said using article 49.3 would be a "defeat for Borne, the government and the president."

"But in the short term, it's a false suspense. Everyone is raising the tension. But it's very unlikely that the government needs to use the 49.3 because they will have a majority," he told reporters.