Mr Gershkovich, a US citizen, was detained by the Federal Security Service (FSB) on 29 March on charges of espionage that carry up to 20 years in prison.

He is the first US journalist to be detained on spy charges in Russia since the Cold War.

The reporter denies all the charges but will remain in prison until his trial.

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Russia claims that Mr Gershkovich was caught "red-handed" and the FSB, the main successor to the Soviet-era KGB, said he was trying to obtain military secrets.

The extended pre-trial detention - which was ruled upon by Moscow's Lefortovo district court on Tuesday - was for "up to 10 months," but the court set the deadline for 30 January in 63 days' time.

The decision prompted backlash from The Wall Street Journal, which said that Russia's continued imprisonment of Mr Gershkovich was a "brazen and outrageous attack" on a free press.

It called for his immediate release.

"Evan has now been unjustly imprisoned for nearly 250 days, and every day is a day too long," the Journal said in a statement.

"The accusations against him are categorically false and his continued imprisonment is a brazen and outrageous attack on a free press, which is critical for a free society. We continue to stand with Evan and call for his immediate release."

President Joe Biden has previously called Mr Gershkovich's detention "totally illegal" while the US embassy in Moscow said it was "deeply concerned" by the court's latest decision.

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Diplomats suspect that Mr Gershkovich was detained as part of broader efforts by Russia to build up a number of arrested US citizens who could be swapped for Russian citizens - and convicted spies - detained in the West.

But Russia has said there could be no exchange involving the reporter until a verdict is reached in his case.

A date for his trial is yet to be announced.

Born to Soviet migrants and raised in New Jersey, Mr Gershkovich moved to Moscow in late 2017 to join the English-language Moscow Times, and subsequently worked for the French news agency Agence France-Presse.

He joined The Wall Street Journal in 2022.

He has appealed against his detention several times, each time appearing in the glass cages used for suspects in Russian courts, but they have all been rejected.

The US State Department has repeatedly told all citizens to leave Russia immediately due to "the potential for harassment and the singling out of US citizens for detention by Russian government security officials".