The leaders of Uganda's main political opposition parties are meeting in talks aimed at fronting a joint candidate to challenge the country's long-serving leader in elections next year.

Three-time presidential challenger Kizza Besigye, believed to be the front-runner for joint opposition candidate, faces competition from former Ugandan Prime Minister Amama Mbabazi. Mbabazi announced his presidential ambitions earlier this year after falling out with President Yoweri Museveni.

Francis Mwijukye, an aide to Besigye, said they are waiting anxiously for the decision of the umbrella group, called the Democratic Alliance.

Uganda's opposition leaders hope to agree on a strong candidate who might mimic the success in Nigeria of President Muhammadu Buhari, whose coalition defeated an incumbent president.

Analysts say Museveni, in power since 1986, is vulnerable against a united opposition.