A man who claims to be equipped with explosives is holding 11 hostages, including children, at a Ukrainian post office.

Police have surrounded the Ukrposhta building in the city of Kharkov, where the man barricaded himself inside from around 3pm on Saturday afternoon (30 December). He is claimed to be wearing an explosive belt.

Police chief Oleg Bekh told local media that the authorities believe there are two children and nine adults being held hostage, although this is still unconfirmed. He also said the unidentified man is acting calm, has not made any demands, and is in regular contact with officers through the hostages' telephones. His motives are unknown.

Bekh added: "We are trying to do everything to maintain communication with him and to do everything that is necessary to ensure the people are released."

National Police spokesman Yaroslav Trakalo told Ukrainskaya Pravda: "According to preliminary information, a man inside the Ukrainian post [office] announced that he is wearing an explosive device, which he is ready to use."

Oleksandr Pertsovskyi, deputy CEO of the Ukrainian post service Ukrposhta, said three of the captives are employees and the others are members of the public. "We just hope it will come off favourably," he told the Kyiv Post.

Dozens of emergency vehicles have sealed off the road and surrounding cafes and shops are closed.