The Foreign Office initially advised against all but essential travel to the country in May, but further updated its guidance on Wednesday (13 July).
A spokesperson for the FCDO said: "A State of Emergency has been declared and an island wide curfew imposed. You should remain in your residence or hotel and not travel at this time.
"Those with a flight ticket will be able to travel to the airport. Sri Lanka is experiencing a severe economic crisis which has led to shortages of basic necessities including medicines, cooking gas, fuel and food."
Travellers have also been made aware of a "major shortage" of fuel in the country, as well as the destination’s ambulance service being "severely impacted" by the ongoing situation.
Tui cancelled its Sri Lanka programme for the rest of July owing to the "ongoing political and economic instability" in the country.