The head of Russian military intelligence, which has been accused of involvement with the Salisbury Novichok attack, has died, the Kremlin has announced.
General Colonel Igor Korobov died from a “serious and long illness” on Wednesday, the Russian Defence Ministry told the state-backed TASS news agency.
The 63-year-old was hailed as a “true son of Russia” and had led the Main Directorate of the General Staff of the Russian Armed Forces, also known as the GRU, for several years.
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Two GRU officers from the agency are accused of travelling to the UK and attempting to assassinate Sergei Skripal, a former GRU Colonel, in March this year.
"The leadership of the Defence Ministry of the Russian Federation, General Staff of the Armed Forces of the Russian Federation (GSA) and Main Directorate of the General Staff of the Armed Forces of the Russian Federation inform with great sadness that on 21 November 2018, after a serious and long illness, head of the (GRU), Deputy Chief of the GSA Colonel General Korobov Igor Valentinovich passed away at the age of 63," a statement said.
"The memory of a wonderful person, a true son of Russia, a patriot of the Fatherland Colonel General Korobov Igor Valentinovich will forever remain in our hearts. We express condolences to his family and friends."
Life expectancy of incumbents 'is pretty low'
General Korobov had worked in military intelligence since 1985 and was made head of the GRU in 2016 by Russian President Vladimir Putin.
In the same year he was the subject of US sanctions for “acts for or on behalf of the GRU”.
In October he was reported to have fallen ill, after having come under heavy criticism for failings by the agency.
Michael Carpenter, a Russia adviser for Barack Obama's administration, tweeted on Thursday: "His predecessor died in 2016 of a heart attack. Life expectancy for incumbents of this job is pretty low, but then so is the median life expectancy in Russia."
In September this year, Prime Minister Theresa May announced that two Russian nationals had been identified as suspects over the Salisbury attack.
The men were believed to be GRU officers and have travelled under the aliases of Alexander Petrov and Ruslan Boshirov.
The Prime Minister described the agency as a "highly disciplined organisation with a well-established chain of command".
Following a widely-dismissed television denial, in which the pair claimed they were simply tourists visiting the cathedral city, their 'real' identities were revealed weeks later.
Investigative website Bellingcat said it had established Boshirov's true identity, reporting he was actually Colonel Anatoliy Chepiga, a highly decorated officer in the GRU.
Bellingcat later said Petrov's real identity was Alexander Mishkin, a military doctor in the GRU.
Both men had been awarded the Hero of the Russian Federation from Mr Putin, the investigators said.
Mr Skripal was given refuge in the UK in 2010 after a "spy-swap" which saw 10 Russian sleeper agents expelled from the United States.
Accused of acting as a double agent after leaving the GRU in 1999, he was serving a 13-year prison sentence for allegedly working for MI6.
Russia has denied all allegations.