Witnesses say police charged the crowd moments after the rally began.
Police have repeatedly tried to ban or disperse rallies by Mr. Chiluba's rivals in recent months. But he continued to give mixed signals about his intentions to run for a third term, which is illegal under Zambia's constitution. Mr. Chiluba said he intends to leave office at the end of his term, but added he supports the idea of calling a national referendum on amending the constitution to allow for a third term. The decision to call a referendum must be approved by his new government.