NAIROBI, Kenya — Ten aid workers detained in South Sudan last week have been freed after the rebel group holding them confirmed their identities as representatives of relief agencies, the rebels said on Monday.

Lam Paul Gabriel, a spokesman for the rebel group, the SPLM-IO, said that its fighters detained the aid workers on Wednesday at a checkpoint in rebel-held territory in the southern part of the country.

He said that the aid workers, all South Sudanese citizens, were transferred to two rebel bases before being flown by the International Committee of the Red Cross to Juba, the capital, on Monday afternoon.

Mr. Lam said this was the second time in a month that the rebel group had detained aid workers in the region for traveling in rebel-held territory without giving notice.