Foreign Office officials have said they are "urgently seeking further information" following explosions at Ataturk Airport in Istanbul, Turkey, in which at least 31 people were killed and dozens injured.
Defence Secretary Philip Hammond described himself as "shocked" and said "we stand ready to help" after reports from Turkey suggested up to three attackers detonated the explosives at the entrance of the international terminal before breaching the X-ray security check and opening fire.
Police are believed to have returned fire in an attempt to minimise the number of casualties.
Prime Minister David Cameron described the terrorist attack as "hideous".
Cameron, in Brussels for what is likely to be his final EU summit meeting with fellow leaders, said the UK would continue to work with the other countries after Brexit on "keeping our countries safe, keeping our people safe - and it's particularly important to say that tonight again when there has been another hideous terrorist attack in Turkey".
Foreign Office officials have said they are "urgently seeking further information" following the explosions.
A Foreign Office spokesman said: "We are in close contact with authorities in Istanbul and urgently seeking further information following an incident at Ataturk airport.
"Our staff in Istanbul and London stand ready to support any British nationals affected."
A spokesman for the Association of British Travel Agents (Abta) said: "Following an incident at Istanbul Ataturk airport, travellers to Istanbul are advised to follow the advice of the local authorities and the Foreign and Commonwealth Office.
"The Foreign Office currently advises that British tourists visiting Turkey should avoid demonstrations or large gatherings and remain vigilant."
Turkey has suffered several deadly attacks in recent months which have been blamed on Kurdish separatists or IS.