A British national was on board the AirAsia plane carrying 162 people that went missing in bad weather Sunday en route from Indonesia to Singapore, the foreign ministry said.
"We have been informed by the local authorities that one British national was on board," a ministry statement read.
"Their next of kin has been informed, and we stand ready to provide consular assistance," it said.
British media identified the passenger as Chi Man Choi, a manager working for Alstom Power electricity company in Indonesia.
The reports said he was travelling with his two-year-old daughter Zoe, who has Singaporean nationality.
His wife and son travelled on an earlier flight.
Air traffic controllers lost contact with the Airbus A320-200 around an hour after it left Juanda international airport at Surabaya in east Java, at 5:20 am (2220 GMT Saturday).
Shortly before disappearing, the plane asked permission from Jakarta air traffic control to deviate from its flight plan and climb above bad weather in an area noted for severe thunderstorms.