Ukraine's Security Service (SBU) demands that the hostages who are being held by separatists who seized the office of the SBU branch in Luhansk region be released.

"The anti-terrorist unit of the Security Service of Ukraine, which is working on freeing the administrative building of the SBU branch in Luhansk region from the radicals who seized it, found that the attackers had placed bombs in the building," the SBU press center said in a statement posted on its Web site on Tuesday.

"Threatening them with weapons and explosives, the separatists are forcibly holding about 60 people, keeping them from leaving the premises and going home," the press center said, adding that such actions qualify as terrorism.

The Security Service of Ukraine demanded the attackers should release the hostages, allow them to leave the building freely, lay down their arms and remove the bombs from the building.

There are no employees of the local SBU branch among the hostages, an informed source told Interfax-Ukraine. "These are local civilians," he said.