France accused Azerbaijan on Tuesday, January 9 of holding a French national arbitrarily and demanded his immediate release after Baku's envoy to France said the man had been arrested on suspicion of espionage, Reuters reports.

Ties between the two countries have been strained in recent months and have worsened since Azerbaijan took control of Nagorno-Karabakh in September.

Azerbaijan's ambassador to France, Leyla Abdoullayeva, told Reuters earlier on Tuesday the French citizen, Martin Ryan, was arrested on Dec. 4 on "suspicion of carrying out acts of espionage".

In a statement sent to Reuters, France's foreign ministry confirmed the detention.

"We are in close contact with his family and the French embassy in Baku was able to visit our compatriot twice as part of consular protection," the ministry said, adding that it had asked to see him again.

"As we have already had the opportunity to indicate to the Azerbaijani authorities, we consider this detention to be arbitrary and demand the immediate release of our compatriot.”

Abdoullayeva said legal authorities in Azerbaijan had ordered Ryan be initially held for four months and that the French embassy had been notified of the arrest.

Baku on Dec. 26 expelled two French diplomats saying they were acting in a way that was "incompatible with their diplomatic status".

France's foreign ministry, which denied the Azeri claims, the next day summoned Abdoullayeva and said it was expelling two Azeri diplomats in response.