Nairobi/Abuja, Aug 2 (DPA) The death toll in recent bloody clashes in the town of Maiduguri and other northern Nigerian districts was stated by police and military sources Sunday to have been more than 600, well above earlier estimates of between 300 and 400.

A spokeswoman for the Red Cross in Maiduguri was quoted as saying there was a real danger of disease breaking out on a large scale as hundreds of bodies had been left out on the open streets for days.

The first mass burials were reported to be going ahead at the weekend following the clashes, involving the Nigerian military plus local security forces, and followers of the Boko Haram Islamic sect.

Police Friday had announced the death of the sect's leader Mohammed Yusuf, hailing the 39-year-old's killing as a victory over extremism, but human rights workers called for an investigation.

Yusuf was shot Thursday night as security forces cracked down on his followers. A police spokesman said he had been 'killed by security forces in a shootout while trying to escape'.