KAMPALA, Uganda—The Ugandan government has started returning assets worth $375 million to Libya's new leaders, which it had frozen last year in line with the United Nations sanctions against the regime of Moammar Gadhafi, Ugandan officials said Wednesday.

Uganda's foreign-affairs ministry said that following the lifting of the sanctions by the U.N. Security Council last December, a process has started to ensure that all the frozen assets are returned to the North African nation.

"All...