Iran has denied reports that supreme leader Ayatollah Ali Khamenei wrote to US President Barack Obama in response to an October letter mooting cooperation against the Islamic State group.
The Wall Street Journal reported on Friday that Khamenei, who has the final say in all matters of state in Iran, had sent a secret but noncommittal letter to Obama in response to his overture.
But in a statement released late on Sunday, the foreign ministry denied there had been any new correspondence.
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"The US president has already previously written letters and in some cases there have been replies," ministry spokeswoman Marzieh Afkham said.
"There has been no new letter."
The Journal reported that Khamenei had raised an array of historic grievances against the United States in his response to Obama's letter, which suggested cooperation against IS if Iran reaches a deal with world powers on its controversial nuclear programme.
Tehran is a staunch ally of both Baghdad and Damascus in their fights against the jihadists but has kept its distance from the US-led coalition carrying out air campaigns in the two countries.