A former HSBC banker has been found guilty by a US jury of defrauding a UK-headquartered energy firm in a $3.5bn (£2.7bn) currency trade.

Mark Johnson, who was HSBC's head of global cash foreign exchange trading, was found guilty on nine counts, in a court room in Brooklyn, New York.

Mr Johnson, 51, was accused of exploiting confidential information from Cairn Energy in 2011 to "front run" the oil and gas firm in the currency markets, thus making an $8m profit for the bank at the expense of its client.

Jurors heard a tape of Mr Johnson saying "Oh, f*cking Christmas" on learning of Cairn's decision to proceed with the trade.

The verdict on Monday followed a month-long trial.

Mr Johnson had been arrested by US federal agents at New York's Kennedy Airport in July 2016 as he was about to board a flight to the UK

He is the first banker to be tried in relation to currency rigging, a scandal that has seen global investment banks pay $10bn in regulatory fines.

The Justice Department is also seeking the extradition of Johnson's former HSBC colleague and alleged co-conspirator Stuart Scott.

HSBC itself is in settlement talks with US regulators and the Justice Department over currency trading.

"This sends a signal to traders and banks that this type of behaviour is absolutely inappropriate and will be pursued by the government," said Michael Weinstein, a former Justice Department attorney, quoted by Bloomberg.