At least 14 unidentified dead bodies were found in Benghazi, Libya's second largest city, officials confirmed on Saturday.
The bodies with gun shots to their heads, taken by the members of the Red Crescent society were brought to a local hospital on Friday, Xinhua news agency reported.
UN envoy to Libya, Martin Kobler expressed his shock and dismay made by the killings, calling them a "war crime" in a Twitter post.
No group has so far claimed responsibility for the executions.