The chairman of Credit Suisse, Antonio Horta-Osório, broke Covid rules for a second time and may have committed a criminal offence in order to attend the Wimbleton tennis finals in London in July, it has emerged.

The latest breach, first reported by Reuters, was discovered through a preliminary investigation by Credit Suisse’s legal team, which found that the former Lloyds Banking Group chief executive broke British quarantine rules by attending the Wimbleton tournament on 10 and 11 July.

The Portuguese banker had flown in from Switzerland, which had been on the UK government’s amber list of countries that required arrivals to isolate for 10 days.

Breaching quarantine rules is a criminal offence, according to UK government guidance, which states that police could issue offenders with fines starting at £1,000 and rising to £10,000 for repeat offences.

A government spokesperson would not comment on individual cases, but explained breaches could also result in jail time in some circumstances. “Passengers are responsible for ensuring they comply with all travel rules, including providing accurate information on their passenger locator form, and failure to do so could lead to a fine or imprisonment.”

The news comes just weeks after Horta-Osório admitted that he breached Covid rules in Switzerland at the end of November, having flown out of the country within three days of arriving on 28 November, despite being required to quarantine for 10 days.

Horta-Osório could face a fine worth up to 5,000 Swiss francs (£4,000) if he is found guilty of breaching Swiss rules by authorities reviewing the case in the country’s canton of St Gallen.

It is a further embarrassment for the investment bank and wealth manager, which recruited Horta-Osório in an attempt to clean up its reputation after a string of scandals, including the dual collapse of Greensill Capital and Archegos Capital earlier this year, as well as findings that it had spied on former staff.

The chairman joined Credit Suisse in April after a decade at Lloyds, where he was tasked with returning the bank to profit and private ownership amid a spate of scandals of its own. Lloyds is still dealing with the fallout of a £245m loan scam at the HBOS Reading branch that predated his appointment in 2011, as well as suggestions the bank tried to cover up the scam.

Credit Suisse declined to comment.