West African presidents said at a crisis summit on Mali 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 civil leaders to secure a national unity government that could 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, the leaders also asked for an end to hostilities between all parties in Mali before the Ramadan Muslim 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 March 22 coup, which allowed ethnic Tuareg separatists and Al-Qaeda-linked Islamists 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 the UN world heritage-listed desert city of Timbuktu.

The Economic Community of West African States regional body has sought to help restore political stability in Mali and offered to send an intervention force of 3,300 troops into the northern conflict zone.

The top ECOWAS mediator, Burkina Faso's President Blaise Compaore, told the meeting of politicians, religious and trade union leaders that a new government must "confront the terrorist peril in the north".

ECOWAS chairman Alassane Ouattara, the president of Ivory Coast, told the meeting -- also attended by 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 roadmap to end the crisis".

And they asked "all parties taking part in the crisis for a complete end to hostilities before the month of Ramadan".

A summit source added that if a national unity government was not in place by the end of July, ECOWAS would no longer recognise the government of Mali and the country could be suspended from sub-regional groups.

The meeting took place in the absence of Mali's interim president Dioncounda Traore, who has been receiving medical treatment in Paris since he was attacked by a mob in his office in May.

Also absent was Prime Minister Cheikh Modibo Diarra, whose relations with ECOWAS have been strained.

Representatives from Mali's north walked out just before the opening of the meeting, for unknown reasons.

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

The Popular Movement of March 22, which supports the coup, staged a protest rally in Bamako of "patriotic" groups against the ECOWAS meeting. Organisers said 500 rallied while police put the figure at 250.

"This meeting is a protest against the meeting organized by ECOWAS," a rally organiser, Nouhoum Keita, told AFP, stressing that the people of Mali alone must create a national unity government.

Keita said a national convention would be held July 14-16.

The coup -- which soldiers justified by saying they were too poorly equipped to fight the northern rebels -- has left Mali effectively split in two, with Islamist controlling an area larger than France or Texas.

The UN Security Council in a resolution Thursday expressed "deep concern" at the presence of Al-Qaeda in 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.