Boris Johnson accepted a £14,000 trip to Saudi Arabia from the country’s foreign affairs ministry only a few days before the journalist Jamal Khashoggi was brutally murdered in the country’s consulate in Istanbul.

Fresh disclosures in the register of members’ interests reveal that the former foreign secretary visited Jeddah on a three-day trip in September, where travel, food and accommodation were all provided for him.

A source close to Johnson said he had “visited Saudi Arabia to discuss his long-standing campaign of improving education for women and girls” during the trip from 19 to 21 September.

Khashoggi, a journalist with the Washington Post and a critic of the Saudi regime, was killed on 2 October in a premeditated killing involving 18 suspects. It has raised questions about whether the country’s ruling crown prince, Mohammed bin Salman, was aware of the plan.

The Johnson source said the Conservative MP has “denounced the murder of Jamal Khashoggi and continues to believe that the UK must hold Saudi Arabia to account for this barbaric act”. Taxpayer funds were not used on the trip.

Jon Trickett, Labour’s shadow minister for the cabinet office, said: “This is yet another reminder of how far the Tories’ cosy relationship with the murderous Saudi regime extends.”

The updated register also revealed that Johnson had accepted a £50,000 donation from Jon Wood, who founded the hedge fund SRG global, at the beginning of October to pay for office and staffing costs.

Wood, a Tory donor, once took legal action against the then Labour government after it nationalised Northern Rock at the time of financial crisis at a time when he was an investor in it.

Johnson also earns £275,000 a year from his Daily Telegraph column, which he took up after quitting the government over Theresa May’s Brexit policy last July. He has repeatedly criticised her approach since but declined to mount a formal leadership challenge.