Four Ukrainians were on board a UN helicopter hijacked by al-Shabab militants in central Somalia this week, the Ukrainian Foreign Ministry said on Friday.

The hijacked UN helicopter was carrying nine people and was carrying out a medical evacuation when a technical problem forced it to make an emergency landing near the Islamist group-controlled village of Hindere.

"Our citizens were members of the helicopter crew of the UN Mission in Somalia... Their identities have been established", - said the representative of Ukraine Oleg Nikolenko.

He said the helicopter belonged to a private Ukrainian company working for the UN and that the government was contacting it to coordinate efforts.

Sources previously told Reuters that Egyptian, Ugandan and Somali nationals were also on board the helicopter. The sources asked to remain anonymous due to the sensitivity of the matter.

Somalia's government said Thursday it was working to rescue the hostages, but the military said that would be difficult in the area controlled by al-Shabab for more than a decade.

According to Reuters, one person on board the helicopter was allegedly killed and six were taken hostage. Two people escaped and their whereabouts are unknown.

All UN flights in the area have been suspended until further notice.