The protests were the largest yet against French President Emmanuel Macron's pension reform plans and come as the French Senate debates the proposals.

Labour unions had called for strikes to "bring France to a standstill" in opposition.

A number of trains and flights were cancelled. The delivery of fuel was blocked to all refineries in the country, according to CGT.

Road blockades were reported in some cities and people walked off the job in schools, at garbage disposal services and at the EDF electricity company.

The pension reforms are central to Macron's agenda in a country with one of the earliest retirement ages in the world.

As well as well increasing the pensionable age, the centre-right government wants to increase the minimum monthly pension to around €1,200 ($1,300).

A pension will continue to be paid out without deductions at the age of 67 regardless of the number of years the person has paid into the system. Many people in France already work past 62 if they have not paid in long enough for a full pension.

French unions are seeking to continue placing pressure on the government and have called for strikes to continue as soon as Wednesday. Prolonged strikes have been threatened at the SNCF railway company and at waste disposal.

Protests against the pension reforms are also planned for Saturday, according to the broadcaster BFMTV.

According to a recent survey by public opinion research institute IFOP, about two-thirds of French people are against the pension reform. Opposition is even stronger among younger people under 35.

Still, the survey found that only about of third of French people believe that protests could halt reform.