A Russian court has found the US journalist Evan Gershkovich guilty of espionage and sentenced him to 16 years in prison, after a trial widely described as a sham.

Gershkovich, 32, denied the charges and pleaded not guilty during the secretive court proceedings in Yekaterinburg, mostly held behind closed doors. His employer, the Wall Street Journal, described the verdict as a “disgraceful, sham conviction”.

The trial was concluded with unusual haste, raising hopes of a prisoner swap involving the journalist, something that has long been the subject of private discussions between Russian and US officials.

Footage from the courtroom showed Gershkovich, dressed in a T-shirt, watching impassively from inside a glass defendant’s box, as the judge read out the sentence of “imprisonment for a term of 16 years in a penal colony with a strict regime”.

The court ordered his mobile phone and reporter’s notebook to be destroyed. Earlier on Friday, the prosecution had asked for an 18-year jail term.

President Joe Biden said the US government was pushing hard for Gershkovich’s release, adding: “There is no question that Russia is wrongfully detaining Evan. Journalism is not a crime.” The British prime minister, Keir Starmer, called the sentence “despicable”.

Gershkovich was arrested while reporting in the Urals city of Yekaterinburg last March, becoming the first US journalist since the cold war to be accused of spying in Russia. He had been held in Moscow’s notorious Lefortovo prison, but was returned to Yekaterinburg for trial.

The prosecutors claimed Gershkovich was collecting secret information about a military factory in the Urals involved in Moscow’s war effort in Ukraine on the orders of the CIA, a claim he, the Wall Street Journal and the US state department have dismissed as ludicrous. He had been granted official accreditation to work as a journalist by the Russian foreign ministry.

“This disgraceful, sham conviction comes after Evan has spent 478 days in prison, wrongfully detained, away from his family and friends, prevented from reporting, all for doing his job as a journalist,” the Wall Street Journal said in a statement released after the verdict.

“We will continue to do everything possible to press for Evan’s release and to support his family. Journalism is not a crime, and we will not rest until he’s released. This must end now.” .

The press freedom organisation Reporters Without Borders described the sentence as “outrageous” and called for Gershkovich to be released immediately.

The US embassy in Moscow said: “Regardless of what Russian authorities claim, Evan is a journalist. He did not commit any illegal actions. Russian authorities have been unable to provide evidence that he committed a crime or justification for Evan’s continued detention.”

The trial was held behind closed doors, which is common in espionage cases. Journalists were allowed briefly into the courtroom when the hearings began last month. Gershkovich appeared with a shaved head, in line with Russian regulations.

Russia’s foreign minister, Sergei Lavrov, claimed on Wednesday that Moscow had “irrefutable evidence” Gershkovich was involved in espionage, but gave no details. Russian authorities have made nothing public that would suggest guilt, and many see the arrest as an attempt to use jailed Americans as bargaining chips in an exchange for Russian intelligence operatives and assassins held in western jails.

The speed of the case, with this week’s hearings brought forward by more than a month and the prosecution racing through witness testimony in one afternoon, may indicate that a long-discussed swap deal is close. Russia usually concludes court proceedings in such instances before a swap.

Vladimir Putin, in an interview in February with the US broadcaster Tucker Carlson, said discussions on a swap were under way. “The special services are in contact with one another. They are talking … I believe an agreement can be reached,” the president said.

He hinted that Russia would like to exchange Gershkovich for Vadim Krasikov, who is serving time in a German jail for assassinating a Chechen exile in Berlin in 2019.