ZAGREB (Reuters) - Croatian Prime Minister Zoran Milanovic said on Wednesday the government could not confirm "with 100 percent certainty" the death of a Croatian hostage purportedly beheaded by Sinai Province, the Egyptian offshoot of Islamic State.

He told reporters at a news conference that authorities have been trying to confirm the authenticity of a still photo being circulated on Twitter by social media accounts supportive of Sinai Province that showed a headless body.

(Reporting by Igor Ilic; Writing by Yara Bayoumy; editing by John Stonestreet)