Incumbent Nicolas Maduro has been declared the winner of Sunday’s presidential election, but the opposition said they were preparing to dispute the results.

Elvis Amoroso, president of the CNE electoral authority, said Maduro secured a third six-year term with 51.2 percent of the vote. Opposition candidate Edmundo Gonzalez Urrutia, who had been leading in opinion polls, got 44.2 percent, he said.

The electoral authority, which is controlled by Maduro loyalists, did not immediately release the tallies from each of the 30,000 polling stations nationwide.

Opposition representatives said earlier that tallies they collected from campaign representatives at the centres had shown Gonzalez trouncing Maduro.

In comments shortly after the announcement, Maduro said his re-election was a triumph of peace and stability and reiterated his campaign trail claims that the voting system was transparent.

Maduro, 61, first won power in 2013 after his mentor, socialist Hugo Chavez, died from cancer. He has been accused of locking up critics and harassing the opposition and has failed to end a years-long economic crisis that has prompted more than seven million of Venezuela’s 30 million citizens to emigrate.

The opposition campaigned on a promise to end the economic crisis and exit polls suggested they stood a strong chance of beating Maduro.

Gonzalez replaced popular opposition leader Maria Corina Machado on the ticket after authorities loyal to Maduro excluded her from the race.

Machado, who campaigned far and wide for her proxy, had urged voters late on Sunday to keep “vigil” at their polling stations in the “decisive hours” of counting amid widespread fears of fraud. She said Gonzalez had won 70 percent of the vote.

“We want the whole world to know that we won in every sector and every state in the country. We know what happened today. We’ve been making sure all the information was collected and reported. This shows the results. It is irrefutable,” Corina Machado told a rally.

Gonzalez, also disputing the official results, told supporters in Caracas the government had violated “all rules and norms…to an extent that we were denied seeing most of the ballots”.

“Our struggle continues and we’ll not rest until the will of the Venezuelan people is respected,” said Gonzalez, though emphasising that he would not call his supporters to take to the streets or carry out acts of violence.