Foreign Secretary Boris Johnson has apologised to the Saudi government after an activist tried to carry out a citizen's arrest of one of the Gulf state's generals.
An anti-war campaigner attempted to arrest Maj Gen Ahmed Asiri over Saudi Arabia's involvement in the conflict in Yemen - while another protester threw an egg at the senior officer as he arrived at an event in London.
Mr Johnson "expressed his regret" at the incident during a phone call with Saudi Deputy Crown Prince Mohammed bin Salman.
The incident on Thursday saw Arab coalition spokesman Maj Gen Asiri confronted as he arrived at an event in London.
The Foreign Office confirmed that Mr Johnson discussed the incident during a phone call on Saturday.
A spokeswoman said: "The Foreign Secretary spoke to Saudi Deputy Crown Prince Mohammed bin Salman on Saturday.
"They discussed bilateral relations, regional issues and the humanitarian situation in Yemen.
"The Foreign Secretary expressed his regret at the disturbance to Saudi Major General Asiri's visit to London on Thursday."
Peace campaigner Sam Walton, who attempted to make the arrest, said he was "delighted to have caused a diplomatic incident".
Mr Walton said he was "disgusted but not surprised" that Mr Johnson had gone "grovelling" to the Saudis.