Paul N. Whelan, the former US Marine who was sentenced to 16 years in prison in Russia on espionage charges, has been unable to contact his family or the US embassy since July 4, and relatives and members of Congress are increasingly concerned about his welfare. His.

“No one has heard from him,” said Haley Stevens, a Michigan Democrat who represents Mr. Whelan, in an interview. “We haven’t heard from him or really been able to speak to him since the beginning of July.”

Ms. Stevens and the family members of Mr. Whelan and Trevor Reed, another former Marine who has been sentenced to prison terms in Russia, will hold a press conference to discuss detention conditions and press for new Congressional resolutions calling for their release.

Speaking to the Capitol on Thursday, Ms. Stevens said Mr. Whelan had to work in a prison clothing factory six days a week, injuring his arm and being held by Russia for 944 days.

“That’s 944 days he’s been away from his friends and family,” Ms. Stevens said at the press conference. “It’s 944 days too long.”

In early June, Mr Whelan interviewed CNN, after which the Russian authorities restricted his access to cell phones, although he was still allowed to call his family. President Biden raised the cases of Mr Whelan, 51, and Mr Reed, 30, during his June summit with Russian President Vladimir V. Putin.

Mr. Whelan called his parents in early July and then a second on July 4th.

“At that time he said, ‘If you don’t hear from me tomorrow, there will be trouble,'” said Elizabeth Whelan, his sister, in an interview.

Since then, neither the US embassy in Moscow nor Mr. Whelan’s parents have been able to contact him, Ms. Whelan said.

Joey Reed, Mr Reed’s father, said Thursday that his son had Covid and that he hadn’t heard from him in more than two weeks. “We are very concerned about his health,” he said. “Both of our families are concerned that Paul and Trevor might die in a Russian prison because of the poor conditions and lack of medical care.”

Evidence against Mr Whelan is thin, and nothing Russian prosecutors have produced has convinced American officials that he was spying on Russia.

Mr Whelan was arrested in late 2018 and, following his conviction last year, was detained in the IK-17 labor camp in Mordovia, about eight hours from Moscow.

Ms. Whelan said she believed her brother was returned to camp after being taken to hospital for treatment for an arm injury. But Mrs. Stevens said it was not clear where the Russians were holding him now. She also said that he was in solitary confinement.

Ms. Stevens, the Congresswoman, said, “The reality is that there has been no contact with him. This reaches another crucial moment. ”

Congress passed a resolution on Mr Whelan in 2019, but new action is in order, Ms Stevens said. She added that a vote would hardly force Mr Whelan’s release, but would demonstrate bipartisan opposition to Moscow’s tactics and “get under the skin of Russia.”

Rep. August Pfluger, the Texas Republican who represents the district Mr. Reed is from, urged Mr. Biden to step up pressure on Russia.

“We won’t compromise until we get Trevor and Paul home,” he said. “We will not tolerate American citizens being illegally detained by the Putin regime.”

Ms. Stevens said Moscow was trying to use Mr. Whelan and Mr. Reed to its own advantage.

“Americans absolutely cannot be used as political pawns for other countries, period, end of story, unacceptable,” she said. “These are the Russians who engage in the dark arts of political interference. I think this is part of an attempt to play with the inner psychology of our political structure. “