US President Barack Obama recently sent a “secret message” to Iran’s leadership regarding negotiations over its nuclear program, the Islamic republic’s semi-official Fars news agency reported Monday night.

The report said Obama had sent a letter to Iranian leaders through Iraqi Prime Minister Haider al-Abadi. It did not detail the contents of the missive.

“An official of one of the neighboring countries has recently brought a message from the US president to our country’s officials,” parliament member Mehrdad Bazrpash told Fars.

Bazrpash claimed that US officials were hypocritical in their communications with Iran. While private messages were respectful of Iran’s leaders, he said, statements made in public were of a threatening nature.

In recent years Obama has been reported to have sent secret letters to Iranian Supreme Leader Ayatollah Ali Khamenei on several occasions. Those messages reportedly dealt with nuclear negotiations and the need to confront Islamic State jihadists in Iraq and Syria. Iran is rumored to have responded with letters of its own.

None of the letters has been officially acknowledged by US officials.

Iran’s foreign minister was due back in Vienna Tuesday accompanied by top advisors and bearing guidance from Tehran that major powers hope will seal marathon negotiations for a historic nuclear deal.

After almost two years of talks, a nominal deadline of midnight (2200 GMT) for an accord was widely expected to be missed, but officials said the negotiations will only last for a few more days.

Foreign Minister Mohammad Javad Zarif flew to Tehran for consultations late Sunday after an intense weekend of talks with other foreign ministers including US Secretary of State John Kerry.

He was expected to return on Tuesday. Iran’s official IRNA news agency said he would be accompanied by his country’s nuclear chief Ali Akbar Salehi, as well as President Hassan Rouhani’s brother and close confidante, Hossein Fereydoun.