Ian Heywood, 47, was kept in solitary confinement for 25 days after being arrested, The Mail on Sunday reported.

He was taken into custody while on his way to Bahrain with a group of colleagues. Police seized him as he was about to board a flight at Doha airport in Qatar.

Heywood is free on bail but cannot leave Qatar until prosecutors decide whether to charge him, the newspaper said.

On Saturday, the Foreign Office in London said Qatari officials had verbally confirmed his arrest to them after eight days. The ministry said they did not tell Heywood's family of his whereabouts until they received official notification of this arrest.

Heywood, who worked for British Airways for 26 years, joined Qatar Airways in May last year as vice president of global sales and distribution. He was then recruited by rival British airline.

"This all started with a commercial dispute that probably has something to do with him leaving Qatar Airways," said Tory Philip Hammond. "The next thing, he was being accused of taking secret information from Qatar Airways with him.