(CNN) The US Embassy in Moscow on Friday formally requested "immediate" consular access to detained American citizen Paul Whelan over his allegations that he has been injured while in custody, according to embassy spokesperson Andrea Kalan.

Whelan was detained in Russia late last year on espionage charges, an allegation he denies. His family maintains he had traveled to Russia to attend a wedding and that he was entrapped and falsely arrested.

"The health and welfare of U.S. citizens abroad is our highest priority," Kalan wrote Friday on Twitter.

Whelan, a discharged US Marine reservist who is also a citizen of the UK, Canada and Ireland, made the complaint during a court hearing Friday on whether to extend his pretrial detention, during which he also complained that his rights were being violated and prosecutors were acting on behalf of the Federal Security Service, Russia's domestic intelligence service.

At the end of the hearing at Moscow's Lefortovo court, the judge overseeing the case extended Whelan's detention until October 29.

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