Russia's top security agency says an American reporter for the Wall Street Journal has been arrested on espionage charges.

On Thursday, local time, Russia's Federal Security Service (FSB) said that Evan Gershkovich was detained in the Ural Mountains city of Yekaterinburg while allegedly trying to obtain classified information.

Mr Gershkovich told a Moscow court on Thursday that he was not guilty of espionage, the state TASS news agency reported.

The same court ruled that Mr Gershkovich should be held in pre-trial custody for nearly two months, until May 29, according to a court document.

Separately, Mr Gershkovich's lawyer, Daniil Berman, told journalists outside the courtroom that he was not admitted to the trial, and that Mr Gershkovich would likely be held in the Lefortovo pre-trial detention centre, which is often used by Russia's FSB security service.

Mr Gershkovich is the first American reporter for a US news outlet to be arrested on espionage charges in Russia since the Cold War.

His arrest comes amid the bitter tensions between Moscow and Washington over fighting in Ukraine.

US 'condemns' the Kremlin

The news drew quick condemnation from US President Joe Biden's administration, which said officials had been in touch with Mr Gershkovich's employer and family.

In the strongest possible terms, we condemn the Kremlin’s continued attempts to intimidate, repress, and punish journalists and civil society voices," Secretary of State Antony Blinken said in a statement.

The White House said the State Department was in direct contact with the Russian government over his detention and urged US citizens living or travelling in Russia to depart immediately.

"These espionage charges are ridiculous. The targeting of American citizens by the Russian government is unacceptable," White House press secretary Karine Jean-Pierre said at a news briefing.

Earlier in a statement, Ms Jean-Pierre said the White House was "deeply concerned by the troubling reports" of Mr Gershkovich's arrest.

The FSB alleged that Mr Gershkovich was acting on the US orders to collect information about the activities of one of the enterprises of the Russian military industrial complex that constitutes a state secret.

"The illegal activities of the correspondent of the Moscow bureau of the American newspaper The Wall Street Journal, US citizen Evan Gershkovich, born in 1991, accredited at the Russian Foreign Ministry, suspected of espionage in the interests of the American government, have been suppressed," the statement continued.

The FSB did not say when the arrest took place.

However, the Kremlin said it understood that Mr Gershkovich had been caught "red-handed".

A spokeswoman for Russia's Foreign Ministry said on Thursday that it would grant the US consular access to Mr Gershkovich "in due course".