About 56 Ukrainians who were being held hostage since Sunday by pro-Moscow groups were released Wednesday from the State Security building in Luhansk in eastern Ukraine, even as the nation's interim government gave a final warning to protesters to enter talks or face “force.”

Ukraine’s interior minister Arsen Avakov reportedly promised that the crisis will be resolved in 48 hours regardless of the protesters' next move, in an attempt to convey Ukraine's willingness to use force if necessary against activists supporting Russia, who have taken over government buildings in the three eastern cities of Kharkiv, Luhansk and Donetsk since the weekend. Ukraine's Security Service had earlier demanded that the hostages be released and the area be cleared of mines and weapons, while the prosecutor’s office in Luhansk opened a criminal case against anti-government protesters.

"There are two options…political and negotiations - and force. For those who want dialogue, we propose talks and a political solution. For the minority who want conflict they will get a forceful answer from the Ukrainian authorities," Avakov reportedly said, according to BBC.

Ukrainian authorities, and the U.S., have repeatedly claimed that Moscow is looking for a reason to invade Ukraine.

“What we see from Russia is an illegal and illegitimate effort to destabilize a sovereign state and create a contrived crisis with paid operatives,” Kerry said, in testimony before a Senate committee on Tuesday, adding: “It is clear that Russian special forces and agents have been the catalyst behind the chaos of the last 24 hours.”

Russia, which has warned Ukraine against using force on anti-government protesters, has denied allegations that it is interested in attacking Ukraine.

“The U.S. and Ukraine have no reasons for concerns,” the Russian foreign ministry said, in a statement Wednesday, according to the Washington Post, adding: “Russia has said many times that it is not conducting any unusual or unplanned activities significant in terms of military issues on its territory in the area of the Ukrainian border.”