Pro-Russian rebels in eastern Ukraine are reported have released two U.S. aid workers captured some 10 days ago.
The two were believed to be among a group of some 30 staff of the International Rescue Committee (IRC) detained when separatists raided their Donetsk offices.
In a statement, IRC head David Miliband said two of the seized aid workers "were now in a safe location," without elaborating.
"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.
Speaking to AFP, a U.S. Embassy spokesman in Kyiv could not confirm the reported release.
The leader of the separatists in the Donetsk region, Aleksandr Zakharchenko, said on May 9 the two had been freed after being detained for alleged spying.
Zakharchenko claimed one of the U.S. aid workers was a "CIA agent."