Zambia’s President Hakainde Hichilema pledged to build on the economic turnaround achieved during his first term as he was sworn in for a new mandate Tuesday after tense elections.

Hichilema took the oath of office with the main opposition leader — who was the runner-up in the August 13 ballot — under arrest on treason charges that he rejects.

The vote was marred by allegations of intimidation, pro-government bias and restrictions on the opposition, tarnishing the copper-rich country’s democratic reputation.

Thousands of cheering supporters wearing the red colours of Hichilema’s UPND party packed the Lusaka stadium for his swearing-in ceremony attended by a handful of African leaders.

“Having done the heavy lifting in our first term, the next five years is all about growth, expansion, opportunity and prosperity for all our people,” he said in an address to the packed stadium.