Russian rebels in eastern Ukraine have released two US aid workers captured some 10 days ago, ABC News quoted authorities of self-proclaimed Donetsk People's Republic as saying early Saturday.

The two Americans were among a group of 37 International Rescue Committee (IRC) staff, when separatists raided their Donetsk offices and detained them at gunpoint. IRC head David Miliband, a former British Labour politician, said two of the seized aid workers "were now in a safe location," but he did not elaborate.

"Every day, the world's humanitarian workers show great courage, taking risks to help the most vulnerable in crisis situations. They should never be targeted," Miliband said in the statement.

The rebel leader in the separatist Donetsk region, Aleksander Zakharchenko, said the two Americans were detained for spying, but have been freed. Zakharchenko claimed one of the US aid workers was a "CIA agent and the other one was recruited."

According to Maria Petrova, spokeswoman for the DNR Security Service, charges against the IRC included the claim that IRC had worked in front-line areas where they gathered information on the deployment of troops.

The rebels accused the aid workers of making contact with various DNR officials in a bid to "gather information."