A Ugandan opposition group has launched a legal challenge against the disputed re-election of long-time President Yoweri Museveni to get his victory nullified over alleged irregularities.

The group, known as Go Forward, on Tuesday filed the challenge in Uganda's Supreme Court. Go Forward's candidate in the presidential election, held last month, was former Prime Minister Amama Mbabazi.

Severino Twinobusingye, a lawyer for Mbabazi, said Tuesday that his client believes he had more support than the 1.43 percent he obtained according to the official tally.

Museveni won with about 60 percent of the votes and his nearest rival, opposition leader Kizza Besigye, got about 35 percent.

Besigye, who is under house arrest, has not filed a legal challenge, saying doing so would "legitimize" what he called a fraudulent election.