Thousands of trucks blocked motorways across France on Saturday for the second time in a month to protest at the government's controversial plans for a tax on heavy vehicles.

The interior ministry estimated 2,200 trucks while organisers said 4,500 lined motorways, driving slowly and clogging up traffic into Paris and other regions.

Two weeks ago around the same number of trucks blockaded roads and caused hours of traffic delays.

"We are satisfied by the mobilisation and we are welcomed by the motorists who let us pass and to whom we distribute leaflets", a spokesman from the road transport federation OTRE told AFP.

France's National Road Information Centre said traffic was circulating slowly in around 20 zones and traffic jams stretched for 16 kilometres (9 miles) in the Paris region and 51 kilometres in other areas.

French President Francois Hollande's government has already been forced to suspend the planned introduction of a new environmental "ecotax" on commercial vehicles carrying cargo of more than 3.5 tonnes after violent protests in Brittany, a predominantly agricultural region in northwestern France.

Opponents of the tax, which critics say unfairly penalises remote areas dependent on deliveries by road freight, are demanding it be scrapped altogether.