LIZ TRUSS’S chief of staff has been questioned by the FBI as a witness in its investigation into an alleged plot to subvert the democracy of Puerto Rico. 

Mark Fullbrook, who ran the PM’s leadership campaign, was interviewed over work he did for Julio Herrera Velutini, a Venuzuelan-Italian banker accused of bribing a Puerto Rican governor, according to reports at the weekend. 

The London-based owner of Puerto Rico bank, Bancredito, is said to have offered to contribute to Wanda Vazquez Garced’s campaign for re-election as governor in return for her sacking the Caribbean island’s financial regulator, according to the US indictment. 

The regulator was at that time investigating Mr Herrera Velutini’s bank. It is alleged that he offered support worth $300,000 (£263,700). 

The banker is also a Tory donor, who has given more than £500,000 to the party since 2019 through his company Britannia Financial Services. The proceedings in the US have sparked anger in the UK and calls for the Tories to give the money back in light of the allegations against Mr Herrea Velutini. 

Mr Fullbrook is involved in the investigation because he was working at the time for political consultancy firm CT. Mr Herrera Velutini was paying CT for consultancy services that might have helped Ms Vazquez Garced in her re-election bid. 

In the end, Ms Vazquez Garced did fire the regulator, but was not re-elected as governor. 

Mr Herrera Velutini denies wrongdoing and is contesting the charges against him, which carry a total maximum penalty of 20 years in jail. The former governor also denies any wrongdoing. 

According to the Sunday Times, the FBI approached the National Crime Agency and Metropolitan Police in April to secure an interview with Mr Fullbrook. He agreed and his company was forced to hand over thousands of sensitive emails. 

He is being treated as a witness. 

A spokesman for Mr Fullbrook said: “He is committed to and complies with all laws and regulations in any jurisdiction in which he works and is confident he has done so in this matter.

“Indeed, Mark Fullbrook is a witness in this matter and has fully, completely and voluntarily engaged with the US authorities.

“The work was engaged only by Mr Herrera Velutini and only to conduct opinion research for him and no-one else.

“Mr Fullbrook never did any work for, nor presented any research findings to, the governor or her campaign.”