A fourth person has died following deadly riots in Kenya on Saturday during a rally for a proposed new constitution.

Dozens were injured - some suffering gunshot wounds - when supporters clashed with opponents of the new charter in the western town of Kisumu.

Police are being criticized for opening fire at the rally. But commissioner Hussein Ali defended the use of live ammunition, saying police acted appropriately to contain a situation that could have spiraled out of control.

At least 46 people were arrested during the riot and are due to be charged in court Monday.

Violence has marred several rallies during the run-up to the referendum on the constitution, set for November 21, which has caused deep divisions within the government.

Critics say the new Kenyan constitution fails to create a strong prime ministerial post, designed in an earlier version to curb the president's sweeping powers.