A plane has been hijacked and forced to land in Sudan, apparently by a group of Eritrean asylum seekers.
Eritrean and Nigerian deportees were aboard the aircraft, Libya says
The hijackers of the plane - which was deporting the Eritreans from Libya - later surrendered to security forces. No-one was badly hurt, reports said.
One Sudanese official said the hijackers were hoping to find asylum in Sudan rather than return to Eritrea.
According to human rights groups, Eritreans who are forcibly repatriated face detention and torture.
Michael Lindenbauer, the UN High Commissioner for Refugees deputy representative in Khartoum, said the plane had left southern Libya for Eritrea, and landed at about 1400 local time (1100 GMT) at Khartoum airport.
One Libyan crew member is believed to have been slightly injured.
Tarek Abu Saleh, a Sudanese foreign ministry official who was at Khartoum airport at the time, said 20 suspected hijackers were now in Sudanese custody.
A senior Sudanese official told Reuters news agency that Libya had refused the Eritreans refugee status and that the Libyan authorities had chartered a plane to take them home.
The plane was heading for the Eritrean capital Asmara when some of the occupants seized control, he said.
Libya's official news agency Jana news agency quoted the country's interior ministry as saying that the plane was carrying "illegal immigrants" - 145 Nigerians and
84 Eritreans - and that knives were used to force it to land in Khartoum.
A BBC correspondent in Cairo, Nick Thorpe, says the plane has now left Khartoum and it is not yet clear what will happen to the Eritreans who were not arrested.
During the long years of conflict in Eritrea, hundreds of thousands of people sought refuge in neighbouring Sudan.
Three years ago, they began returning home under a scheme co-ordinated by the UN and the Eritrean government.
But the human rights situation in the country remains dire, according to Amnesty International. UNHCR says 4,402 Eritreans sought asylum in Europe and north America last year, a figure that has more than tripled since 2000.