Socialist candidate Nicolas Maduro has won a narrow victory in Venezuela’s presidential poll.
Mr. Maduro, who was chosen by the late Hugo Chavez as his successor, won 50.7% of the vote against 49.1% for opposition candidate Henrique Capriles.
The electoral commission said the results were “irreversible”.
Mr. Capriles said he refused to accept the result without a recount, and said he believed that Mr Maduro had lost the election.
He said there were more than 300,000 incidents from Sunday’s poll that would need to be examined.
“This result does not reflect the reality of the country. We will do everything so that the truth is known,” Mr. Capriles said.
Earlier, Mr. Maduro had addressed his supporters, saying he had spoken to Mr. Capriles on the phone, and that he would allow an audit of the election result.
He called for those who had not voted for him to “work together” for the country.
Mr. Maduro, wearing the colours of the Venezuelan flag, told a rally of supporters in front of the presidential palace that he had won a “just, legal and constitutional” victory.
His supporters set off fireworks in the capital, Caracas, after the result was announced, while opposition voters banged pots and pans, Reuters news agency reports.
But Mr. Maduro’s margin of victory was far smaller than that gained by the late President Chavez over Mr. Capriles at elections last October.
Almost 80% of eligible voters took part in the poll.
Mr. Maduro had been serving as acting president since Mr. Chavez died of cancer on 5 March.
He is due to be sworn in on 19 April and serve until January 2019 to complete the six-year term that Mr. Chavez would have begun in January.
Mr. Chavez was a divisive leader. To his supporters he was the reforming president whose idiosyncratic brand of socialism defeated the political elite and gave hope to the poorest Venezuelans.
He effectively used his country’s vast oil reserves to boost Venezuela’s international clout, and his strident criticism of the US won him many political allies in Latin America.
However, his political opponents accused him of being an autocrat, intent on building a one-party state.
Mr. Chavez bequeaths a nation beset by crumbling infrastructure, unsustainable public spending and under-performing industry.
Read more: BBC News