Law enforcement officers stand guard at the scene after police freed all hostages from a bus and arrested the armed man in Lutsk, Ukraine on Tuesday. Photo: AFP

Ukrainian police freed 13 hostages and arrested an armed man who held them on a bus for more than 12 hours on Tuesday, after the country's president agreed to his demand to post a movie recommendation on social media.

The  Security Service of Ukraine (SBU) said a joint operation had resulted in all the hostages being released unharmed after a police stand-off in the western city Lutsk with the man, who threatened to detonate an explosive device unless his strange requests were met.

The tense hostage situation seemed to be resolved swiftly after the man spoke on the phone with Ukrainian President Volodymyr Zelensky, who then recorded a short video, apparently meeting one of the man's demands.

Three hostages were quickly let go, followed by the rest about an hour later. 

Footage published by Ukrainian officials showed police escorting people as armed special forces stood over a man lying face down on the pavement near the bus with his hands behind his back.

The hostage-taker had earlier fired shots and thrown an explosive package into the street in the center of Lutsk, a city of over 200,000 some 400 kilometers from capital Kiev.

The man was identified as Maksym Kryvosh, 44, who had previously spent around 10 years in prison on various charges.

An account which was later suspended by Twitter had posts under Kryvosh's name claiming he was armed, including with bombs, and demanding top Ukrainian personalities convey anti-establishment messages on social media.

AFP