Minsk - A tower collapsed in a castle used as a prison by the Belarusian government, Belapan news agency reported on Monday.

The western bastion of the Pishchalovskiy fortress, a 19th century brick-and-mortar fortress in Minsk, crashed down shortly after midnight.

The collapse of the 30-metre tower was audible throughout Minsk's Romanov neighbourhood, a low-rent industrial district. The massive building of formerly four circular towers, is one of the most visible structures in the region.

No one was injured in the collapse, and no prisoners escaped, a prison official said.

Illegal modifications to the tower by the prison administration, and lack of proper maintenance to the 19th century structure, were the most likely causes of the collapse, said Anton Astapovich, a government cultural conservation official.

Oleg Slepchenko, an Interior Ministry spokesman, confirmed the western tower of the prison had crumbled, but declined further comment.

The Pishchalovskiy fortress was purpose-built in 1825 to incarcerate prisoners of the state. The Gothic-style castle, complete with a curtain wall and crenelations, is still used by Belarus' authoritarian government as a penitentiary.

A state commission reviewing the building's foundations in 2004 said the prison's walls and towers were in need of emergency repair.

Money was unavailable for the project, sparking news reports the next year that the prison would be sold to foreign developers and re- opened as a hotel. No investor was found.

Belarus' leader, President Aleksander Lukashenko, is a pariah among most western nations for his authoritarian government and a 1996 constitutional coup giving almost total control over the country.

Foreign investment in the former Soviet republic is negligible, with less than 1 per cent of Belarus' GDP coming from external sources, since Lukashenko came to power. (dpa)