Nearly 200 people died when a boat carrying undocumented immigrants caught fire in the Red Sea off Sudan, a state-run news agency said Wednesday.

Three people were rescued and 197 were thought to have drowned although a search for survivors was continuing, the Sudanese Media Center said, citing unnamed sources.

The fire, the cause of which was unknown, broke out in Sudanese waters after the ship had been sailing for four hours from the North African country, the agency said.

The four Yemeni owners of the Cuban-flagged boat were arrested, it said.

The victims were immigrants from surrounding African countries who were trying to cross the Red Sea to Saudi Arabia. The operation was planned and implemented in Tokar, 150 kilometres south of Port Sudan near the Eritrean border, the report said.

It did not say when the fire broke out.

It said authorities had thwarted another attempt in the Tokar area to smuggle 247 immigrants from countries that included Chad, Nigeria, Somalia and Eritrea.