The British Foreign Office has updated its travel advice to warn that further terrorist attacks in Tunisia are possible following the beach resort massacre in Sousse, which left at least 38 people dead, Sky News reported on Sunday.

The update was made last night, just hours after Foreign Secretary Philip Hammond said that his office would review its current advice.

The advice on its website now reads: "Further terrorist attacks in Tunisia, including in tourist resorts, are possible, including by individuals who are unknown to the authorities and whose actions are inspired by terrorist groups via social media.

"You should be especially vigilant at this time and follow the advice of Tunisian security authorities and your tour operator."

At least 38 people died after gunman Seifeddine Yacoubi opened fire in Port el Kantaoui on the outskirts of Sousse two days ago.

The British death toll has risen to 15.

Up to 2,500 more people could return to the UK from Tunisia today, as part of holiday firms' efforts to get those on holiday at the beach resort home as soon as possible.