Nigeria plans to start evacuating nearly 3,000 of its nationals, mostly students, from Sudan by a convoy of buses to Egypt this week, a top official said on Monday.

Foreign countries are rushing to get their nationals out of Sudan as fighting between forces loyal to two rival generals rages into a second week.

Western nations have sent special forces and military aircraft to help get out embassy staff and other nationals. Others have fled the capital Khartoum by road.

Onimode Bandele, special duties director for Nigeria's National Emergency Management Agency, NEMA, told Channels TV the plan was to move about 2,650 to 2,800, including families of embassy staff.

"Nobody has been evacuated yet," he said. "There are plans to get buses to start movement tomorrow morning."

Officials say a total of around 5,000 Nigerian nationals could be looking for evacuation.

Since fighting erupted, at least 427 people have been killed and more than 3,700 wounded, according to UN agencies.

They also reported Sudanese civilians fleeing areas affected by fighting, including to Chad, Egypt and South Sudan.