The son of a top aide to London mayor Boris Johnson has died in Thailand, sources said.
Andrew Lister, 28, son of deputy mayor and chief of staff Sir Edward Lister, was believed to have fallen ill in the room of his guesthouse on the holiday island of Koh Phangan.
He had reportedly been drinking with friends.
Yesterday, a spokesman for the Foreign Office said: “We can confirm the death of a British national in Koh Phangan, Thailand, on September 12.
“We are in touch with the family and helping them at this difficult time.”
The Mail on Sunday quoted a Thai police spokesman as saying: “Witnesses said Andrew John Lister was drinking with four friends in room 315 on the Baan Talay Guesthouse on Haad Rin Beach when he collapsed.
“Attempts were made to revive him but they failed.
“His body was taken to the local hospital. We believe he died of a heart attack.
“There was no evidence of drugs in the room.”
A Greater London Authority spokesman confirmed the death, and said: “It’s an extremely sad time for the family and we urge all to respect their privacy.”
Sir Edward landed the £127,784 post in May 2011.
He advises Mr Johnson on strategic planning applications and has oversight of the London Plan and Community Infrastructure Levy.
As the mayor’s chief of staff he leads on GLA budgets and administration. Before entering City Hall, Sir Edward served as leader of Wandsworth Council from 1992 to 2011.
Reports said Andrew Lister collapsed after attending the island’s monthly Full Moon Party, which attracts tens of thousands of people.