Cannes' promenade was pretty enough before authorities installed a row of 400 giant flowerpots. But the potted plants aren't there to look good - they are a security measure to avert terrorist attacks during the film festival.

View of the Suquet, old city area of Cannes, before the start of the festival.

The Cannes festival, which begins on Wednesday, is the first since the attack in nearby Nice last July, when a Tunisian man drove a 19-tonne truck into a crowd celebrating Bastille Day on the promenade, killing at least 80 people.

The shoulder-high flower pots along the Cannes Croisette are supposed to acting as discreet concrete barriers that should stop any similar car or truck attack.

The police have also invested in 160 meters (175 yards) of spiked chains that can stop a truck, deployed extra forces and called on a battalion of civilians volunteers to inform them of any suspect activity.

Some 550 security cameras are keeping an eye on things, too, said Yves Daros, head of the municipal police.

"It's the densest (camera) network in France. In Cannes, we have a camera for every 140 inhabitants," Daros told Reuters TV.

France has been under a state of emergency since November 2015 when coordinated gun and bomb attacks in Paris killed 130 people and wounded 368. Just last month, a policeman was shot dead in central Paris - the most recent in a string of attacks claimed by Islamist militants.

The U.S. State Department has a long-standing travel alert for France and some other European countries, warning Americans to be on their guard around potential targets such as "high-profile events".

The French police have no information about a specific threat, but few events in France have a higher profile than the annual film festival. This year, Will Smith and Nicole Kidman will be among the Hollywood A-listers.

70th Cannes Film Festival - Cannes, France. 15/05/2017 - French policemen arrive at the festival palace.

U.S. film critic Scott Roxborough said people were aware of the security risk, but not afraid to come.

"The talent might be a bit more worried about having to come to a festival and might not be 100 percent secure, but given the fact that with the studios it's about money and about business, I think that overweighs things."

The local police chief said that while budget cuts were hitting public spending around France, security was one area where expense was not being spared.

"The state has put in more resources this year than ever in the past," Daros said.

The Cannes Film Festival runs from May 17 to May 28.

Source: Reuters