WASHINGTON, May 1 (Xinhua)-- U.S. President George W. Bush said Tuesday that the coming international conference on Iraq's security will test both Iran and Syria's seriousness to play constructive role in Iraq.

    "Iran and Syria have been invited to attend. This will be an important test of whether these regimes are truly interested in playing a constructive role in Iraq," Bush said in a speech TAMPA, Florida.

    The international conference on Iraqi issue is due to be held in Egypt's Red Sea resort of Sharm el-Sheikh on May 3-4. It will group all of Iraq's neighbors, the five permanent UN Security Council members, plus representatives from the United Nations, the European Union, Canada, Germany and Japan.

    Both U.S. Secretary of State Condoleezza Rice and Iranian Foreign Minister Manouchehr Mottaki will attend the international conference.

    Rice said on Sunday she would not rule out talks with Iranian officials at the meeting. Iran said it was ready to have discussion with the U.S., but ruled out dialogue with Rice at Iraq conference.

    "For the moment the conditions do not exist for such a dialogue," Iranian Deputy Foreign Minister Mehdi Mostafavi said Tuesday.

    The U.S. accuses both Iran and Syria of backing anti-American insurgents in Iraq as well as U.S.-designated terrorist groups elsewhere in the Middle East. ¡¡