The British government on Thursday told all UK tourists to leave Tunisia because a terrorist attack is “highly likely” and the country’s government has not done enough to enhance security, reports The Associated Press (AP).

The Foreign Office advised against all but essential travel to Tunisia, a popular holiday destination for Britons. It added that British tourists on package holidays should contact their travel agents, which will arrange flights to bring them home.

The warning comes two weeks after 38 tourists, 30 of them British, were killed when a gunman stormed the Tunisian beach resort of Sousse.

In March, 22 people died in an attack at the National Bardo Museum outside Tunis.

“While we do not have any information suggesting a specific or imminent threat, since the attack in Sousse the intelligence and threat picture has developed considerably leading us to the view that a further terrorist attack is highly likely,” British Foreign Secretary Philip Hammond said, according to AP.

In a statement, his office said the travel advice had been changed because “we do not believe the mitigation measures in place provide adequate protection for British tourists in Tunisia.”

Tunisian authorities have said the terrorist, 23-year-old Seifeddine Rezgui, acted alone during the attack, though they believe he had accomplices who supported him beforehand. Last week there had been eight suspects, including a woman, who remained in custody on suspicion of being directly linked to the attack.

Last Saturday, more than a week after the Sousse attack, Tunisian authorities announced a state of emergency and enacted new security measures such as sending more than 1,300 security forces to patrol hotels, beaches and other tourist sites.

Hammond, speaking on the sidelines of talks about Iran’s nuclear program in Vienna, said British authorities were in close contact with tour operators, who were arranging to get their customers home “as quickly as possible.”

“To those travelling independently, our advice is to return on commercial flights which are operating normally,” he added, according to AP.

The UK decision amounts to a major new blow to Tunisia’s tourist industry. Hundreds of thousands of British tourists visit Tunisia each year. Many Britons left after the Sousse attack, but some 3,000 are still in Tunisia, noted the report.