A petrol tanker slammed into a Nigerian military convoy, killing nearly four dozen soldiers hours after they returned from peacekeeping duties in Sudan's Darfur region, the military said Thursday.

The unit from the Army's 245th Battalion flew Wednesday from Darfur to the international airport in the capital, Abuja, and were heading back to home base by road when the accident occurred overnight, the military said in a statement.

Forty-six soldiers, including one officer, died in the flames after the petroleum tanker collided with two troop-transport vehicles on the road in northern Nigeria. Five other soldiers were treated for their injuries, the military said.

President Umaru Yar'Adua was planning to cut short a trip to Tanzania, where he was attending an African Union meeting, his office said.

"President Yar'Adua deeply regrets that having bravely confronted and survived the hazards of service in strife-ridden Darfur, the gallant soldiers returned home only to lose their lives in a dreadful vehicular collision on their way back to their base." the Presidency said in a statement.

"The president believes that the accidental death of these brave soldiers whilst on national service is an immense loss to the country."

A military burial was planned for Friday in Abuja. Nigeria has at least two battalions of soldiers serving in Darfur at any given time. Troops normally serve several months on the ground there before rotating back home. Seven Nigerian soldiers died in an attack on their base last year in Darfur.

Nigeria, Africa's most populous nation with 140 million people, is the continent's largest supplier of peacekeepers and the country has spearheaded or hosted mediation efforts for many of Africa's hot spots, including Liberia, Sierra Leone and Sudan's Darfur, where rebels have battled government and allied militia forces for years.

Back home, accidents are common on Nigeria's poorly maintained roads. Even main cities are linked by pitted, two-lane roads crammed with passenger buses, trucks laden with goods and rickety private vehicles.

Drivers often travel at high speed and overtake slower vehicles, leading to head-on collisions and high death rates.

In January, a petrol tanker overturned on a road in the southern city of Port Harcourt, spilling its load into a crowded market. Some three dozen people died when the petrol ignited.