The Arab League summit was postponed after officials failed to reach agreement on how to reform the Middle East.
The unexpected decision came 36 hours before the Arab League summit was scheduled to begin on Monday.
The Tunisian foreign ministry said the meeting was put off indefinitely because of differences of opinion regarding ways to encourage reform in the region. Some leaders were on their way to the Tunisian capital when the announcement came.
Foreign ministers of the League's 22 members were discussing a series of reform proposals for the Middle East during two days of preliminary sessions. Earlier Saturday, Arab League secretary-general, Amr Moussa, acknowledged that an agreement had not been reached, but said the foreign ministers were working toward a solution.
At the heart of the debate was the so-called Greater Middle East Initiative, a series of suggestions yet to be officially announced by the United States. Arab countries have widely rejected the notion that reform could be imposed from outside, but differed over ways to promote a comprehensive plan that would still respect individual differences within nations.
The Arab League was founded in 1945 to encourage unity among Arab nations and to oppose Western trends and what the Arab League charter calls Zionist dangers.
The Palestinian-Israeli situation is always on the top of the League's agenda. But after Israel assassinated the Hamas spiritual leader Sheikh Ahmed Yassin last week, the complicated issue of peace between Israel and the Palestinians became tied to the process of reform in the region. Many Arab leaders believe reform cannot succeed without a renewed peace initiative.
Several Arab leaders announced they would not attend the summit, and planned to send lower-ranking officials instead, sparking rumors of discord. Jordan has called on the Arab League to set a new date for the summit as soon as possible.