PARIS (Reuters) - France’s foreign ministry said on Thursday it regretted the arrest of the husband of a detained Iranian human rights lawyer, a rare criticism that is likely to irk Tehran at a time of strained relations.

Reza Khandan is married to Nasrin Sotoudeh, an activist lawyer who served about half of a six-year jail sentence imposed in 2010 for spreading propaganda, then was arrested again in June.

Khandan, who had campaigned for his wife’s release, told Iranian media then she was facing security charges. He said on Facebook on Monday he had been called in for questioning by Iran’s Ministry of Intelligence, and when he objected he was told, “Then you’ll be arrested”.

“France regrets the arrest in Tehran of Reza Khandan, husband of Nasrin Sotoudeh,” Foreign Ministry spokeswoman Agnes von der Muhll said in a statement. “We remain very concerned about Mrs Sotoudeh, who started a hunger strike on Aug. 25, and we hope she and Mr. Khandan are released quickly.”

France rarely comments publicly on human rights issues in Iran. It is now working with Britain and Germany to save a 2015 agreement on Iran’s nuclear program, which was thrown into disarray when U.S. President Donald Trump pulled out of the accord in May and re-imposed economic sanctions on Iran.

Even so, tensions between Paris and Tehran have grown in recent months ass President Emmanuel Macron and his government have become increasingly frustrated with Iran’s regional activities, in particular its ballistic missile program.

Both countries have yet to appoint new ambassadors to each other’s capitals.

Paris also told its diplomats and foreign ministry officials to postpone indefinitely all non-essential travel to Iran, citing a foiled bomb plot and a hardening of Tehran’s attitude toward France.