PARIS (Reuters) - U.S. diplomatic cables released by online whistle-blower WikiLeaks include remarks from an Iran source in 2009 saying Supreme Leader Ayatollah Ali Khamenei has terminal cancer, French daily Le Monde reported.

The source, a non-Iranian businessman based in Central Asia and traveling often to Tehran, “has learned from one of his contacts that (former president Ali Akbar) Rafsanjani told him Supreme Leader Ali Khamenei has terminal stage leukemia and could die in a few months,” according to an August 2009 cable.

The document, written by a U.S. diplomat, says that Rafsanjani, a critic of President Mahmoud Ahmadinejad who has expressed sympathies with Iran’s reformist movement, decided on learning of Khamenei’s illness to start preparing himself to be a successor.

As Supreme Leader since 1989 Khamenei has final say on policy in the Islamic Republic, which is locked in a stand-off with key world powers over the nature of its nuclear activities.

The document cited by Le Monde is one of thousands of cables leaked by the WikiLeaks website at the weekend that reveal confidential views and information from senior U.S. diplomats overseas that would normally remain confidential for decades.

Le Monde, one of a handful of newspapers around the world given access to the cables, said the Iran documents showed Washington relied on a network of Iran-watchers in the Middle East to shed light on a country it sees as an enigma.

The United States broke diplomatic relations with Iran 30 years ago after fundamentalist students in Iran seized the U.S. Embassy in Tehran and held staff there hostage for 444 days.