Tanzania's electoral commission says ruling-party candidate John Magufuli has won the presidential election.
The commission said Thursday that the CCM party's Magufuli defeated main challenger Edward Lowassa of the opposition Chadema party, 58 to 40 percent.
Lowassa had rejected the official results of Sunday's vote before they were announced, citing alleged fraud.
French news agency AFP reports he rejected the results again Thursday and accused the electoral commission of trying to "rob the citizens of Tanzania of their democratic rights."
Tanzania's October 25 elections for president, parliament and local seats had been expected to be the closest in the nation's history. President Jakaya Kikwete is stepping down after completing two five-year terms.
CCM faced its strongest challenge in decades from a coalition of opposition parties led by Chadema.
Zanzibar nullifies votes
On Wednesday, the electoral commission in semi-autonomous Zanzibar nullified voting results there, citing "gross violations" in the voting process. Commission chairman Jecha Salim said there is a need to hold fresh elections in the archipelago.
It was not immediately clear how the nullification would affect the national voting. Zanzibar elects its own government, but its votes count in Tanzania's national presidential election.
The U.S. embassy in Tanzania said it was "gravely alarmed" by the annulment of the Zanzibar results.