An Arab League source said: "So far eight kings and heads of state have said they will not go to Khartoum and that they will be represented by their prime ministers or their foreign ministers."
Confirmed as absences are King Abdullah of Saudi Arabia, Hosni Mubarak, the Egyptian president, King Hamad bin Issa al-Khalifa of Bahrain, Khalifa bin Zayed Al Nahayan, president of the United Arab Emirates, King Mohammed VI of Morocco, Sultan Qaboos of Oman, Jalal Talabani, the president of Iraq, and his Tunisian counterpart Zine el-Abidine bin Ali.
The summit, initially scheduled for two days, will be cut to one and will focus on the situations in Darfur, Iraq and the Israeli-Palestinian conflict.
"It is a wider trend. If there is freedom anywhere, democracy, probably most of these [Arab] regimes would go ... they are a little bit alarmed about it all"
Sudanese Islamic leader
Meanwhile, Hasan al-Turabi, the Sudanese opposition leader who has been frequently jailed by his government, ridiculed the summit saying the annual meeting would only remind Arabs that their leaders had no solutions.
Al-Turabi, an ideologue of Islamist revivalism worldwide, told Reuters on Monday that the leaders who would attend would lose power if they allowed democracy in their countries.
He has said Hamas's victory over Fatah secularists in Palestinian elections in January indicated that Arabs are looking for "an alternative course of life", a trend that is alarming to existing rulers.
Threat of democracy
"It is a wider trend, it's a phenomenon worldwide," he said.
"If there is freedom anywhere, democracy, probably most of these regimes would go... There are pressures from below and above and they are a little bit alarmed about it all.
"The old political parties - leftists, Baathists, Arab nationalists or even the old nationalist parties - they don't have a programme to address present challenges."
The summit will discuss funding
the Palestinian Authority
A former foreign minister and attorney general, al-Turabi said Arab summits had become occasions on which Arab leaders wasted time on diplomatic tactics and meaningless resolutions.
Al-Turabi was detained in 2001 after a power struggle with Omar Hasan al-Bashir, the Sudanese president, and has spent much of the time since then in jail or under house arrest. Released last June, he leads the opposition party the Popular Congress.