HARARE, Zimbabwe (AP) — Zimbabwe's constitutional court is ruling Friday afternoon on the main opposition's challenge to the results of last month's historic presidential election.

Security is tight in the capital, Harare, as the court will determine whether President Emmerson Mnangagwa's narrow victory is valid. The opposition claims vote-rigging and seeks either a fresh election or a declaration that its candidate, Nelson Chamisa, won.

A credible vote is key to lifting international sanctions as the southern African nation tries to move away from the long shadow of Robert Mugabe's 37-year rule.

The July 30 vote was peaceful but scenes of the military sweeping into the capital two days later to disperse opposition protesters led to fears that the government of Mnangagwa, a former Mugabe enforcer, was stuck in the past despite declarations of reforms.