French police on Wednesday detained 79 people after protesters broke into the Paris region's main wholesale market complex during nationwide demonstrations by farmers, a police source told AFP.

The protesters briefly entered a storage area in the Rungis market south of Paris causing damage. They were taken out by security forces, added the source, who asked not to be named.

Television images showed a heavy security presence around the market including gendarmerie armoured vehicles. The extent of the damage was not immediately clear.

The action took place after dozens of farmers from the Lot-et-Garonne department of southwest France arrived at the market.

Earlier, 18 people seeking to blockade Rungis had been arrested for "interfering with traffic", police said. Prosecutors said 15 of them were then taken into custody.

Thousands of farmers from across the country been converging on Paris and other cities, setting up roadblocks to halt traffic on highways in protests which have largely seen the government strike a conciliatory tone.

But Interior Minister Gerald Darmanin has made clear that actions at Rungis, which provides food and other essentials to much of the Paris region of 12 million people, and other key infrastructure such as Paris airports would constitute a red line.