A Russian court on Friday ruled that Paul Whelan, a former United States marine accused of spying should be held in a pre-trial detention facility for a further three months to give investigators more time to look into his case.

Whelan, who holds a US, British, Canadian and Irish passports was detained in a Moscow hotel room on December 28 and accused of espionage, a charge which he denies. If found guilty, he could be jailed for up to 20 years.

Russia’s Federal Security Service detained Whelan after an unidentified individual handed him a thumb drive containing classified information although his lawyer has said his client believed he was being handed holiday snaps.

The case has further strained the already poor US-Russia relations. This is even as the US embassy in Moscow said a consular official had visited Whelan in custody on Thursday.

The embassy however said that it was unable to provide further information as Whelan had not been allowed by investigators to sign a Privacy Act Waiver (PAW) which would legally allow the US government to release information relating to the case.