French academics detained in Iran face Revolutionary Court after being denied bail
French President Emmanuel Macron had called on Tuesday for Iran to release the pair without delay, saying "their imprisonment is intolerable".
Comment: Iranians are caught between biting sanctions and a brutal crackdown
His appeal came on international human rights day and followed a prisoner swap at the weekend between Iran and its arch-enemy the United States.
On Tuesday it was reported that a judge had decided to release the French academics on bail, however, the ruling was opposed by the prosecution and as a result the case has been referred to Iran's Revolutionary Court to settle the dispute, Iran's semi-official ISNA news agency said, citing the pair's lawyer Saeed Dehghan.
The Revolutionary Court typically handles high-profile cases in Iran, including those involving espionage.
"The bail for my clients had been issued and the judge had agreed to their release on bail," Dehghan was quoted as saying.
"Though delayed, this decision was legal, but the deputy prosecutor opposed the opinion of the judge," said the lawyer.
As a result, "the matter must be sent to a competent court to settle disputes... which in this case is the Revolutionary Court."
Marchal had come to Iran to visit Adelkhah and was accused of "collusion against national security", Dehghan said last month, according to ISNA.
But the lawyer said the reasons for the charges were still unknown to him.
The arrest of Adelkhah, a Franco-Iranian specialist in Shia Islam, was confirmed on July 16 by Iran's judicial spokesman Gholamhossein Esmaili, who gave no further details.
Her friends and colleagues in France have said she was accused of espionage.
Tehran, which does not recognise dual nationality, has criticised Paris for "unacceptable interference" in its domestic affairs after the French government sought consular access to Adelkhah.
"The French should not forget that Iran is sovereign and independent," Iranian foreign ministry spokesman Abbas Mousavi wrote on Twitter Wednesday.
"Our government and our judiciary will never accept any advice from anyone... interference in Iran's domestic affairs is unacceptable," the message continued, without making explicit reference to Macron.
Iran said on Monday it was open to more prisoner swaps with the United States after one such exchange at the weekend.
Xiyue Wang, an American scholar who had been serving 10 years on espionage charges, was released by Iran on Saturday in exchange for Massoud Soleimani, an Iranian who had been held in the US for allegedly breaching sanctions.
Adelkhah and Marchal are not the only foreign academics facing charges in Iran.
British-Iranian anthropologist Kameel Ahmady, who was released on bail last month after three months in detention, is suspected of links to foreign intelligence services.
Iran confirmed in September that Australian academic Kylie Moore-Gilbert had been arrested for "spying for another country".