A two-day summit of Arab leaders due to open on Monday has been postponed indefinitely by host country Tunisia.
Secretary General Amr Moussa refused to comment on the decision
A Tunisian foreign ministry spokesman said there had been "disagreements" at a preliminary meeting of Arab foreign ministers over issues to be discussed.
They included plans to relaunch a peace initiative to Israel, and proposals for reforms in the region.
Tunisia said it regretted postponing a summit "on which Arab and international opinion has pinned great hopes".
The BBC's Paul Wood in Tunis said Arab leaders had hoped to use the conference to relaunch a peace initiative with Israel, proposed two years ago.
But after the assassination of Hamas founder Sheikh Yassin by Israel last Monday, few wanted to talk peace with the Jewish state.
Our correspondent says there is also a great deal of friction over plans for political reform in many Arab countries, which are coming under intense pressure from the United States to democratise.
Problems in reaching agreement on the summit agenda prompted some countries, such as Saudi Arabia and Bahrain, to send only low-level delegations, added our correspondent.
The Associated Press quoted diplomats as saying the summit was called off by Tunisian President Zine El Abidine Ben Ali.
The killing of Sheikh Yassin put Arab League peace plans on hold
In a statement, the Tunisian foreign ministry acknowledged "the existence of difference of views" over issues "of great importance to the process of development, modernisation and reform in our Arab countries".
"Tunisia strongly regrets the postponement of this summit on which Arab and international opinion has pinned great hopes considering the delicate situation through which the Arab nation is going and the deadlock of the Palestinian issue after the recent tragic events".
Arab League Secretary General Amr Moussa told reporters "no comment, no comment, no comment" as he left the meeting.
Syrian Foreign Minister Farouk al-Sharaa said: "We hope that the summit should have been convened. We regret it (the postponement). President Bashar Assad was on his
Jordanian Foreign Minister Marwan Moasher called on Arab governments to decide quickly on a new date and place for the summit.