Kampala - Ugandan police on Tuesday fired tear gas at demonstrators protesting President Yoweri Museveni's decision to re-appoint the country's election body, which has been accused of rigging previous elections.

Museveni reluctantly allowed multi-party democracy to be revived in the East African country during the mid 1990s, but opposition parties and human rights groups say the former guerilla leader uses the election body to stay in power.

Several hundred demonstrators, mostly from main opposition party the Forum for Democratic Change (FDC), planned to hand parliament a petition opposing the re- appointment of the seven-member Electoral Commission.

Heavily armed police overpowered the crowd while other officers occupied the FDC headquarters just outside the capital Kampala.

"Seven of our youth have been arrested and many were injured," opposition legislator Nabila Sempala told the German Press Agency dpa. "We are not going to give up and we are going to re-group and organize another systematic demonstration."

Kampala's police commander Andrew Solowen told reporters that the demonstration was illegal and the protestors were disorderly.

Museveni has contested three elections since coming to power in 1986 and is expected to win again in 2011.(dpa)