Moscow (CNN) Paul Whelan, a US national detained by Russian authorities on espionage charges, has now been behind bars for one year, the US embassy in Moscow said Saturday.

"On December 28, 2018, Russian authorities arrested Paul Whelan," US embassy spokesperson Rebecca Ross wrote on Twitter. "365 days. Still no evidence. Still no phone calls to his family despite multiple requests. Still no independent medical care. Enough is enough. Let Paul go home THIS year!"

Whelan -- a former US Marine who is also a citizen of the UK, Canada and Ireland -- was detained at a Moscow hotel last year by Russian authorities who alleged he was involved in an intelligence operation. He has been in Lefortovo prison in Moscow since.

Whelan denies the spying charges and says he has been denied proper medical treatment . His family maintains he traveled to Moscow to attend a wedding and was arrested on false charges.

Paul Whelan holds a message as he stands inside a defendants' cage before a hearing at the Lefortovo Court in Moscow on October 24.

A Russian court this week extended Whelan's detention until March 29 at the request of investigators from Russia's Federal Security Service.

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