WEST African presidents said at a crisis summit on Mali on Saturday that the international war crimes court should probe abuses committed in the country's Islamist-held desert north.

The six leaders also urged Malian political leaders to secure a national unity government to address the crisis that has hit their country since a March 22 military coup accelerated a northern rebel advance.

At a conference in the Burkina Faso capital, Ouagadougou, the leaders also asked for an end to hostilities between all parties in Mali before the Ramadan month of fasting starts on July 20.

However, Mali's president and prime minister were not at the summit, northern representatives walked out, and supporters of the military coup that threw Mali into turmoil staged a counter demonstration in Bamako.

Mali, once a beacon of stability in West Africa, was thrown into chaos by the coup, which allowed ethnic Tuareg separatists and Islamists linked to al-Qaeda to sweep across the north in a rapid offensive.

The Islamists have since chased the Tuareg out of key towns, imposed sharia law, and last week destroyed ancient Muslim shrines they deemed un-Islamic in United Nations (UN) world heritage-listed Timbuktu.

The Economic Community of West African States (Ecowas) has sought to help restore political stability in Mali and offered to send an intervention force of 3300 troops to the northern conflict zone. The top Ecowas mediator, Burkina Faso President Blaise Compaore, told the meeting of politicians, religious and union leaders that a new government must "confront the terrorist peril in the north".

Ecowas chairman Alassane Ouattara, the president of Côte d'Ivoire, told the meeting - also attended by the leaders of Niger, Togo, Benin and Nigeria - that "we cannot tolerate the partition of a brother country".

At the end of the summit, the leaders called for the International Criminal Court to investigate "war crimes" in northern Mali.

"They are asking the International Criminal Court to proceed with necessary investigations to identify those responsible for war crimes and to take the necessary action against them," a statement said.

The group also called on Mali to build a national unity government by July 31 that could "implement a road map to end the crisis". They asked "all parties taking part in the crisis for a complete end to hostilities before the month of Ramadan".

A summit source said if a national unity government was not in place by the end of the month, Ecowas would no longer recognise Mali's government and it could be suspended from subregional groups.

The meeting took place without Mali's interim president, Dioncounda Traore, who has been receiving medical treatment in Paris since a mob attacked him in his office in May. Also absent was Premier Cheick Modibo Diarra, whose relations with Ecowas are strained. Representatives from Mali's north walked out just before the meeting.

Mali's renegade soldiers agreed under intense regional and international pressure to hand power back to a civilian administration after the March coup but have retained considerable influence.

The Popular Movement of March 22 staged a protest rally in Bamako of "patriotic" groups against the Ecowas meeting. Organisers said 500 turned out, while police put the figure at 250.

"This meeting is a protest against the meeting organised by Ecowas," organiser Nouhoum Keita said, stressing that the people of Mali alone must create a national unity government. He said a national convention would be held this week.

The coup has in effect left Mali split in two, with Islamists controlling an area larger than France.

In a resolution on Thursday, t he UN Security Council expressed "deep concern" at the presence of al-Qaeda among the Islamic Maghreb fighters, who have been blamed for kidnappings and attacks in several countries. But the council held back from giving a UN mandate to any West African force that could help Mali's interim government take back the territory.

Sapa-AFP