The head of Russian military intelligence, which is accused of orchestrating the Salisbury Novichok attack, has died.

Igor Korobov died on Wednesday after "a serious and long illness," Russian news agencies reported, citing the defence ministry.

The 63-year-old GRU Chief's death comes after a series of embarrassments for the secretive organisation, for which he was reportedly berated by President Vladimir Putin.

Mr Putin reportedly gave Mr Korobov a personal dressing down last month for the bungled operation to poison former Russian spy Sergei Skripal and his daughter.

Russian journalist Sergey Kanev, who writes for an investigative group funded by Putin foe and former oligarch Mikhail Khodorkovsky, reported that Mr Korobov fell ill after the meeting with Mr Putin.

Evgeny Buzhinsky, a former Russian general, dismissed allegations of foul play. Commenting on suggestions that Mr Korobov's death was untimely, he told the BBC: "No you are completely wrong. It was a long, long struggle against a very bad disease ... In Russia no one is suspicious, believe me."

The defence ministry called General Korobov, who ran the spy agency since 2016, "a wonderful person, a faithful son of Russia and a patriot of his homeland." It did not give further details about his death.