Obama sent 'secret letter' to Iran

US President Barack Obama is said to have written a secret letter to Iran's supreme leader describing a shared interest in fighting Islamic State (ISIS).

The letter, reported by the Wall Street Journal, also urges Ayatollah Ali Khamenei toward a nuclear agreement, reports BBC.

The US president stresses any co-operation on fighting ISIS is contingent on Iran reaching such an agreement by a 24 November diplomatic deadline.

The White House has declined to comment on Obama's "private correspondence".

But Republican senators John McCain and Lindsey Graham said it was "outrageous" that the president would approach Iran, given its support for the Syrian government and Shia groups such as Lebanon's Hezbollah.

"The administration needs to understand that this Iranian regime cares more about trying to weaken America and push us out of the Middle East than cooperating with us," they said in a joint statement.

"The consequences of this ill-conceived bargain would destroy the Syrians' last, best chance to live in freedom from the brutal Assad regime."

 Meanwhile, Interpol has said would-be jihadists have been travelling on cruise ships to reach conflict areas in the Middle East.

The international police body said some of those trying to join militant groups in Iraq and Syria had used cruise lines to get to countries including Turkey.

The US has ruled out inviting Iran to join an international coalition it has assembled against ISIS, but has said Iran has a role to play in the fight against ISIS.

Islamic State, a Sunni jihadist group, poses a threat to Shia-majority Iran and has taken over large parts of Iran's Shia-dominated ally Iraq.