People receive first aid treatment after an explosion in downtown Minsk, Belarus, 04 Jul 2008

Belarusian officials have launched a criminal investigation into a bomb blast that injured about 50 people at an Independence Day concert in the capital, Minsk.

Local authorities say the homemade bomb, rigged with nuts and bolts, exploded overnight Thursday to Friday.

Belarusian President Alexander Lukashenko was at the concert and inspected the site following the blast.

Police have blamed the explosion on "hooliganism."

Belarusian Interior Minister Vladimir Naumov says officials found a second bomb in the same area after the explosion.

Belarusian opposition activists have expressed concern that Mr. Lukashenko might use the incident to further restrict democratic freedom in the former Soviet republic.

The United States and the European Union have accused Mr. Lukashenko of jailing opponents, restricting news media freedom and rigging elections. Western countries have imposed sanctions on him and other officials in his administration.

Independence Day is Belarus' main state holiday, combining celebrations of the 1944 Red Army liberation of Belarus from Nazi forces and the Soviet republic's declaration of sovereignty in 1990.

Some information for this report was provided by AFP and Reuters.