An influential Iraqi cleric living in Iran has issued a fatwa — or a religious decree — against a U.S.-Iraqi security pact that would keep American troops in Iraq for three more years.

The Iranian-born Ayatollah Kazim al-Hosseini al-Haeri calls the proposed agreement "haram" — which in Arabic means "forbidden" by Islam— and says it's "a sin God won't forgive."

Al-Haeri, based in the Iranian holy city of Qom, is believed to be a mentor of anti-U.S. Iraqi Shiite cleric Muqtada al-Sadr whose followers oppose the deal.

The fatwa was posted on al-Haeri's web site Wednesday. The cleric says the U.S. is pressuring the Iraqi government to approve the deal that brings "humiliation and scarifies Iraq's national sovereignty."