President Edgar Lungu of Zambia has taken the oath of office after the nation's top court rejected an opposition petition to block the ceremony.

Lungu, who was re-elected last month in a closely contested vote, was sworn in Tuesday at an event attended by regional leaders, including Robert Mugabe of Zimbabwe and Ian Khama of Botswana.

Lungu had averted a runoff election by winning just over 50 percent of the votes, but the opposition under challenger Hakainde Hichilema alleged there were polling irregularities and went to court.

The political tension was exacerbated by Zambia's economic struggles, which are fueled by the fall in prices of copper, its main export.