Ugandan police officers fired tear gas on Wednesday to disperse thousands of supporters of the opposition leader Kizza Besigye, who had gathered to hear his renewed calls for protests against high food and fuel prices. The rally came a day after a court dismissed charges against him relating to his leading previous demonstrations. At least nine people were killed in the government’s clampdown of the earlier protests, and Mr. Besigye was badly beaten by security agents. Uganda’s president, Yoweri Museveni, who has been in power for 25 years, had blamed drought and global increases in crude oil prices for the rising food and fuel costs. Mr. Besigye had challenged Mr. Museveni in a presidential election in February but came in a distant second in a vote he called rigged.