The head of the investigation into the poisoning of Russian former double agent Sergei Skripal has been appointed as the next head of Britain's domestic intelligence agency.

Ken McCallum led the probe into the 2018 chemical attack in Salisbury, southwest England, that almost killed ex-spy Skripal and his daughter, Yulia.

Russia has repeatedly rejected claims that officers from its GRU military intelligence agency used a powerful nerve agent against Skripal in retribution for his work for Britain and Western agencies.

Both survived after spending days in a coma and have since gone into hiding. A woman who was exposed to the Soviet-era nerve agent Novichok died, and several other people were affected.

The British government announced the appointment of McCallum on Monday. He will take over from the current head of MI5, Andrew Parker, when he retires at the end of April.

McCallum, the current deputy director-general, has nearly 25 years' experience in the security service, and oversaw counter-terrorism operations before and during the 2012 London Olympics.

He has also worked on security issues in Northern Ireland, Islamic extremism and cybersecurity.

McCallum, a maths graduate from Glasgow, described his appointment as a "huge privilege", while Parker said he was "the right person to take MI5 forward".

"He brings a wealth of leadership and national security expertise to the role, which is all the more important today as MI5 and the country deals with the impacts of the Coronavirus pandemic," he added in a statement on the MI5 website.