Somali armed men have released two aid workers kidnapped in the country's southern region nine days ago, a local elder and an aid worker have said.

The Belgian doctor and Danish nurse working for Medecins sans Frontieres (MSF) were released by the armed men without receiving a ransom on Tuesday.

Sheik Mohamed Kheyr, the district commissioner of Rab Dhure, where the pair now are, said elders and an Islamic group helped secure their release.

"The MSF aid workers have been released without condition," said Sheikh Aden Yare, a leader of the opposition al-Shabaab group in Bakol region, where the aid workers were kidnapped.

"They are now with us, and we are going to Hudur to hand over the MSF officers. They are free now. And this will not happen again," Yare said.

MSF confirms release

The pair were taken on April 19 after carrying out a nutrition study, while on their way to Hodur, a town near the Ethiopian border.

Their abductors had demanded a ransom.

A local MSF worker also confirmed their release.

A total of 35 aid workers were killed in Somalia in 2008 and 26 abducted, the UN says.

The attacks have limited the ability of relief agencies to respond to one of Africa's longest humanitarian crisis.

More than three million Somalis - nearly half the population - depend on emergency food aid in a country that has been without an effective central government since 1991.

The Bakol region, near the Ethiopian border, is under the control of an armed opposition group that is fighting Somalia's weak UN-backed government.