Jamaica in January is full of appeal, with the tourist hub of Montego Bay (26C, sun) more enticing than Morecambe Bay (5C, rain).

But the Foreign Office is warning British holidaymakers in the north-west of the island not to wander off from their resorts on their own.

“Tourists should stay in their resorts and limit travel beyond their respective security perimeters,” says the new bulletin.

The only times when they should leave the resorts are for “travel to and from the airport or for excursions”. Transport for these journeys should be arranged by the resort hotels, the FCO advises.

“Most hotels and resorts have assigned Jamaica Tourist Board (JTB) drivers who carry photo ID and display a prominent blue JTB sticker on the front windscreen.”

Even in hotels, holidaymakers are urged to take precautions: “Use the hotel safe, lock windows and doors and report suspicious activity.”

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Jamaica experiences twice as many murders in the average year as Britain, even though the UK has a population 20 times higher.

The murder rate in St James parish, the district which includes Montego Bay, is twice as high as in any other parish; last year there were six killings a week on average.

Prime Minister Andrew Holness has declared a state of public emergency, saying: “Murders have been escalating in the parish of St James.”

Jamaican newspaper The Gleaner reports Major Basil Jarrett of the Jamaica Defence Force as saying: “It is in response to the rampant criminality – the murder rate, the extortion, the general lawlessness in Montego Bay.”

Checkpoints have been set up to monitor all vehicles entering and leaving the parish.

The US government warns its citizens to avoid parts of Montego Bay, where “violence and shootings occur regularly”.

American officials are prohibited from entering some parts of the city, as they are from certain parts of the capital, Kingston.

Virgin Atlantic flies a Jumbo jet from Gatwick to Montego Bay three times a week. Virgin Holidays has just under 200 customers in the area. A spokesperson said: “The safety and security of our customers and staff is always our priority, and we’re working closely with our resorts across Montego Bay.

“In line with Foreign Office guidance we are contacting customers in Montego Bay to advice them to remain in their resort hotels except when on a transfer to or from the airport or on an excursion organised by our agents.”

The long-haul tour operator Kuoni has 10 clients in Montego Bay at present. They have been told not to leave the resort except on an organised excursion.

A spokesperson for Kuoni said: “We are monitoring the situation closely and will keep customers in resort and those due to travel updated with the latest advice if needs be.”

Around 200,000 British holidaymakers are thought to have visited Jamaica last year. The Independent estimates around 5,000 UK visitors are on the island at present.

Unless the Foreign Office warns against travel, holiday firms are likely to maintain existing terms to customers with forward bookings for Jamaica. They will not be able to switch destination or cancel the trip without penalty.