The United States has called on Russia to permit increased access to ex-Marine Paul Whelan, who is being held in Moscow on an espionage charge his supporters say is unfounded.
U.S. Embassy spokeswoman Andrea Kalan said on March 11 that officials would visit the 49-year-old "later this week."
Whelan -- who holds U.S., Irish, Canadian, and British citizenship -- was arrested on December 28 in Moscow and charged with spying. His pretrial detention runs until May 28.
"We urge the Russian government to provide consular officers unrestricted visits with Mr. Whelan, to include discussing his case freely and without obstruction from Russian authorities," Kalan said in a statement on Twitter.
"We urge the Russian govt to allow Whelan to sign documentation that will allow his family to choose & hire an attorney that best represents his interests," she added.
Kalan said in February that the U.S. Embassy had been unable to release any information regarding the case because Russian authorities had not allowed Whelan to give a signed Privacy Act Waiver to the embassy.
If convicted, Whelan could face up to 20 years in prison. His family has said he is innocent and that he was in Moscow to attend a wedding.
Russian officials have not released details of the allegations against Whelan, who they assert was caught red-handed in an act of espionage.
Defense lawyer Vladimir Zherebenkov has suggested his client was set up, saying he was handed a flash drive that he believed contained harmless personal material such as photographs but actually contained classified information.
Whelan, 49, was working as a global security director for a U.S. auto-parts manufacturer at the time of his arrest.
Relations between Russia and the United States have been strained over Russia's alleged interference in the 2016 U.S. presidential election, its seizure of Ukraine's Crimean Peninsula, and its support for separatist militants in eastern Ukraine.
Whelan's detainment came weeks after a Russian woman, Maria Butina, pleaded guilty in a U.S. court to acting as an agent for the Kremlin.
The Kremlin has denied that Butina is a Russian agent and has organized a social-media campaign to secure her release.
In the past, Russia has arrested foreigners with the aim of trading prisoners with other countries.
Zherebenkov has also said that his client is innocent and suggested that Russian officials may be trying to use him in an exchange for Butina.
Russian Deputy Foreign Minister Sergei Ryabkov has rejected that scenario.