Five held in France for urging attacks on G7 police

French and Spanish police have manned security checkpoints between the French down of Hendaye and Irun on the Spanish border. (AFP/IROZ GAIZKA)

The arrests occurred early on Monday, just days ahead of the summit chaired by French President Emmanuel Macron who will from Saturday host the likes of US President Donald Trump, German leader Angela Merkel and Britain's Boris Johnson in the glitzy southwestern resort town of Biarritz.

Speaking to reporters in Biarritz where he inspected security preparations, Interior Minister Christophe Castaner said 13,200 police and gendarmes would secure the event.

They would be backed by members of the armed forces as well as police deployed on the Spanish side of the border, he added.

"The aim is to have maximum security with a minimum of disruption. We will not tolerate any unrest. If it happens, we will respond," he said.

Several of the suspects are young members of radical anti-capitalist groups known as "black blocs" which played a major role in the violent street protests that rocked Paris and other French cities over the last months.

The investigation was triggered after a woman living in the area posted a message online pinpointing a hotel where gendarmes policing the summit will stay.

Four people suspected of issuing calls to "burn down" the hotel were arrested in locations including Hendaye, south of Biarritz, and Loire Valley town of Tours.

One of them has a police record for violence during a demonstration, the source said.

The woman who published the initial message, from the Landes region north of Biarritz, was also detained.

"We are particularly attentive to spreading threats to the security of the G7 on social networks," said Castaner, adding there was no specific threat to the event.

'NON-VIOLENT FREEDOM OS EXPRESSION'

A raft of unprecedented security measures has been put in place ahead of the summit, with the resort on lockdown and its picturesque Grand Plage beach off-limits to everyone except delegates and those accredited for the summit.

Activists will be holding a "counter-summit" some 20 kilometres away, so security forces will be on hand to ensure there are no disruptions in a country that has been hit by months of anti-government protests.

Those protests were spearheaded by so-called "yellow vests" demonstrators angered by social inequalities although hardline black bloc activists also got involved.

Police will be under huge pressure in Biarritz to keep order without resorting to heavy-handed tactics that sometimes marked their response to the street protests.

Since Monday morning, anti-capitalist activists, environmentalists and other anti-globalisation groups have begun rallying in Urrugne near the Spanish border where they have planned a week of protests they insist will be peaceful.

A large anti-G7 rally will take place in the nearby town of Hendaye on Saturday to coincide with the formal opening of the summit.

Castaner said the counter-summit "should be allowed to take place peacefully. There is no question of preventing the non-violent freedom of expression."

He added authorities were conscious of the "terror threat" for such an event while adding there was "no particular alert".