PORT KANTAOUI: Planeloads of shocked foreign tourists flew out of Tunisia Saturday after a beachside massacre claimed by the self-styled Islamic State (IS) militant group killed 38 people and prompted a major security clampdown.

The impoverished North African nation, bracing for a devastating blow to tourism, announced plans to deploy troops at vulnerable sites and shut dozens of mosques accused of inciting extremism.

Many of the victims were from Britain, which announced that at least 15 of its citizens were killed in Friday's gun assault in the popular resort of Port el Kantaoui and that the number “may well rise”.

The Tunisian authorities, facing the difficult task of identifying victims mown down in their beachwear, said the dead also included at least one Belgian and a German.

One woman from Portugal and one from Ireland were said by their governments to have also been killed when the assailant pulled a gun from inside a beach umbrella and opened fire on tourists on the sand and by a pool.

It was the deadliest attack in Tunisia's recent history.

In London, Prime Minister David Cameron warned the country needed to prepare “for the fact that many of those killed in the attack were British”.

He added: “These were innocent holidaymakers, relaxing and enjoying time with their friends and families.”

The shooting followed a March attack claimed by IS on Tunis's National Bardo Museum that killed 21 foreign tourists and a policeman.

“It's very painful,” said Alya, who lives in nearby Sousse. “The wounds were still healing from the Bardo attack, and now we've been dealt an even bigger blow.”

Another 39 people including 25 Britons, seven Tunisians and three Belgians were wounded in Friday's attack, the health ministry said.

Prime Minister Habib Essid on Saturday announced that from next month armed guards would be deployed all along the coast and inside hotels.

Fears for future

But Tunisians who rely on tourism for their livelihoods fear it will come too late.

“If I were in their shoes, I wouldn't set foot in Tunisia right now,” sighed Imed Triki, a shopkeeper in Sousse.

“After this catastrophe, it's normal that they leave the country so quickly. Do they come here on holiday or to die?”

On Saturday, an armed policeman in plain clothes was guarding the beach where the carnage unfolded.

Tourists' personal belongings, abandoned in the panic, were still strewn across the sand.

The attack came on the same day that 26 people were killed at a Shiite mosque in Kuwait and a suspected Islamist attacked a factory in France.

IS claimed both the Kuwait bombing and the Tunisia attack, days ahead of the first anniversary of the group declaring its territory in Iraq and Syria a “caliphate”.

Tunisian Secretary of State for Security Rafik Chelly told Mosaique FM the gunman was a student previously unknown to the authorities.

“He entered by the beach, dressed like someone who was going to swim, and he had a beach umbrella with his gun in it,” Chelly said.

Lucky escape

Witnesses described scenes of panic after the shooting at the hotel on the outskirts of Sousse, about 140 kilometres south of the capital Tunis.

“All I saw was a gun and an umbrella being dropped,” British tourist Ellie Makin told ITV television.

“Then he started firing to the right-hand side of us. If he had fired to the left I don't know what would have happened, but we were very lucky.”

One young Tunisian who witnessed the tragedy told police that the gunman fired only at tourists.

“The terrorist told us: 'Stay away, I didn't come for you',” he said.

“He did not fire at us — he fired at the tourists.”

Pastry cook Slim Brahim told AFP that after mowing down tourists on the beach the gunman then turned on guests by the hotel pool.

“I saw someone fire on elderly tourists. They were killed,” said Brahim, who works at the Riu Imperial Marhaba Hotel that was hit. “Then he threw a grenade by the pool.”

Tightened security

The Tunisian premier said a raft of new anti-terrorism measures would go into effect from July 1, including the deployment of reserve troops to reinforce security at “sensitive sites... and places that could be targets of terrorist attacks”.

He said the government would also close 80 mosques suspected of fanning extremism, echoing his predecessor's calls to shut down “illegal” mosques.

It constituted an “exceptional plan to better secure tourist and archaeological sites”, Essid said.

But tour operators scrambled to fly thousands of fearful holidaymakers home.

Overnight, 13 airliners took off from Enfidha airport north of Sousse.

Travel companies Thomson and First Choice said 10 Thomson Airways flights would be repatriating about 2,500 Thomson and First Choice customers on Saturday.

They said some of their customers had been caught up in the massacre.

Belgian airline Jetair has also announced it would repatriate 2,000 people.

Tourism accounts for seven percent of Tunisia's GDP and almost 400,000 direct and indirect jobs.