Britain's foreign ministry says a plane carrying Foreign Secretary Boris Johnson to Brussels has made an unscheduled landing because of a "technical issue."

The Foreign Office says the Royal Air Force plane carrying Johnson and officials took off from a base in London and landed at Luton Airport northwest of the city on Sunday.

The ministry said that Johnson "thanked the RAF crew for their professionalism and was grateful to Luton Airport for the brief, unscheduled welcome."

It said Johnson continued to Brussels by other means.

Johnson, who helped lead the campaign for Britain to leave the European Union, was appointed foreign secretary by new Prime Minister Theresa May on Wednesday. He will meet EU officials in Brussels for the first time since the referendum result.