Islamic State (IS) has kidnapped around 20 foreign medical workers from a Libyan hospital, according to a CNN report.

The workers were taken from the Ibn Sina Hospital in Sirte during an attack on the building.

The workers are mainly from the Philippines, with others from Ukraine, India and Serbia, according to a hospital official. CNN reports that a group of more than 30 gunmen attacked the hospital while a bus was waiting to take them to the capital, Tripoli.

The hospital workers had decided to leave the city because of the security situation there and the official said that Islamic State wanted them to stay because they were the only people able to treat its wounded fighters.

Sirte was the final stronghold of forces loyal to Colonel Muammar Gaddafi, who was captured there in 2011 by Transitional National Council forces, beaten and shot to death.

IS, which murdered 21 Egyptian Coptic Christians in Libya last month, took control of the city last year. Libya's chaotic security situation has seen it disintegrate as a political unit since Gaddafi's defeat, with warring tribes and interest groups providing fertile ground for the success of IS there.