Long-time Zambian opposition leader Michael Sata is scheduled to be sworn in as the country's next president on Friday, in what will be the country's second democratic transition of power since its independence from Britain.

Zambia's Electoral Commission announced early Friday that the 74-year-old populist leader defeated incumbent candidate Rupiah Banda following a tight presidential race that was marred by scattered reports of violence throughout the country.

With most of the constituencies counted, Mr. Sata received 43 percent of the votes, compared with 36 percent for Mr. Banda.

Supporters of Mr. Sata, some of whom were behind violent protests that had broken out as the country awaited the final results, took to the streets in celebration after the announcement, which came just after midnight local time.

Thursday, police said demonstrators stoned cars and buildings in the north-central cities of Kitwe and Ndola and set fire to a market in Kitwe, amid frustration that the electoral commission was taking too long to announce the results. Many opposition members feared the delay would allow time for the commission to skew the results in Mr. Banda's favor.

Ahead of the poll, Mr. Sata, known as “King Cobra” for his sharp wit and fiery speeches, accused the electoral commission of planning to rig the outcome using pre-marked ballots – an allegation the commission denied.

European Union election observers said Thursday that the elections were “generally well administered,” but unequal access to resources meant there was not a “level playing field” for campaigning.

Specifically, observers criticized state-owned media for failing to meet “even their minimal obligations as public service media,” saying state news programming lacked balance in its coverage of the campaign.

Analysts do not expect many major policy changes when Mr. Sata takes office, though his Patriotic Front party has promised to re-instate a 25 percent windfall tax on mining revenues that Banda's party abolished in 2009.

Mr. Sata's repeatedly accused Mr. Banda of tolerating corruption and not doing enough to ensure that more Zambians share in the wealth of the country's copper reserves. Zambia is Africa's biggest producer of copper.

The two men are long-time rivals. In 2008, Mr. Banda defeated Mr. Sata by two percentage points in a special election triggered by the death of late President Levy Mwanawasa, who died of a stroke.

Mr. Banda's Movement for Multiparty Democracy had ruled the country since former president Frederick Chiluba defeated independence leader Kenneth Kaunda in the country's first democratic elections held in 1991.

Formerly known as Northern Rhodesia, Zambia declared independence from Britain in 1964.