The move comes as tourist arrivals to the island are increasingly following the end of the 30-year ethnic war in May 2009 and ahead of the peak winter tourism season.

The FCO said visitors must have permission from the Sri Lankan Ministry of Defence before travelling to the northern districts of Jaffna, Kilinochchi, Mannar, Mullaittivu and Vavuniya.

Although the war was over, "there is a general threat from terrorism in Sri Lanka," it said.

"Isolated attacks cannot be ruled out and could be indiscriminate.

"Foreign tourists and visitors have not been targeted in the past but attacks have occurred in places frequented by foreigners."

The FCO also advised tourists to be careful of mines and unexploded ordnance.

"Although the conflict is over, extensive military operations are still ongoing, clearing minefields, unexploded ordnance and locating weapon caches," it said.

"Do not venture from the roads or cleared footpaths and if in any doubt, contact the local security authorities for local advice."

It also warned of an increasing number of incidents of credit card fraud, road accidents and drownings.