Several thousand UK holidaymakers remained in resorts in Tunisia on Friday evening after the government declared a state of emergency and imposed a night-time curfew.

Troops had reportedly surrounded Tunis international airport and there were unconfirmed reports the authorities had closed the surrounding air space. However, Monastir airport remained open as Thomas Cook worked to ferry its 1,800 clients back to the UK.

At least 60 people are reported dead after security forces fired on demonstrators demanding an end to the 23-year rule of President Ben Ali. There have been protests across the country, including in the tourist areas of Hammamet and Sousse, but no reports of violence in resorts.

Tui Travel said it was in continual contact with its 1,500 customers, of whom a majority had so far opted to continue their holidays. Up to 5,000 UK tourists are estimated to be in Tunisia in total.

Four of six Thomas Cook Airlines flights planned today to repatriate holidaymakers had returned to the UK or were on their way back at 5.30pm GMT, with a fifth flight preparing for take-off and a sixth on its way to Monastir to pick up passengers.

Thomas Cook had “strongly advised” all its clients to return after the Foreign Office  issued a change in travel advice overnight, advising against all but essential travel to Tunisia.

Tui Travel tour operators Thomson and First Choice gave customers the option of returning or staying, as the Foreign Office has not so far recommended evacuation. However, the companies cancelled all excursions and both Tui and Thomas Cook have cancelled departures to Tunisia on Sunday. The companies are reviewing whether to operate departures scheduled later next week.

Thomson and First Choice clients due to travel on Sunday are advised to call 0800 009 3834 to speak to an advisor.

Tunisia has seen several months of protests over soaring food prices, high unemployment and a high level of corruption. But the violence has shocked tour operators who have previously viewed the country as among the most stable in the region.