A Conservative and Reform UK donor lost out on a knighthood and a peerage amid claims of his involvement in corruption, the high court has heard at the start of his defamation case against the BBC.

An episode of Panorama in 2021 and a BBC article caused “very serious harm” to Mohamed Amersi, his barrister, Oliver Powell, said on Wednesday.

The programme and article alleged strong grounds for suspecting that during Amersi’s work for the Swedish telecoms company Telia he was involved in deals that he knew or should have known were corrupt or involved corrupt payments.

In an opening statement to the high court at the start of a seven-week defamation trial, Powell said the claims made by the BBC went to the heart of Amersi’s reputation and integrity.

The barrister read a witness statement from Amersi, who donated £25,000 to Reform UK last year and who previously donated hundreds of thousands of pounds to the Conservatives .…