Candidates supporting Venezuelan President Nicolas Maduro have secured control of the national congress, the electoral board said on Monday, after a parliamentary election which opposition leaders boycotted because of what they said was fraud.

The electoral board's president, Indira Alfonzo, said in comments broadcast on state television that 67.6% of 5.2 million votes cast in Sunday's election were for pro-Maduro candidates, but only 31% of eligible voters participated in the ballot.

The result returns congress - the last state institution not in the hands of the ruling Socialist Party - to Maduro's allies despite an economy in ruins, U.S. sanctions that stifle the OPEC nation's oil exports and the emigration of some 5 million citizens.

Lines were short at polling places across Venezuela on Sunday as many voters heeded opposition leader Juan Guaido's call for a boycott. In some areas, there were longer queues to buy scarce fuel than to cast a vote.

Members of the new congress will have few tools to improve the lives of people in a country where monthly salaries rarely cover the cost of a day's groceries. Their election will also not improve Maduro's reputation among Western nations for mismanagement and undermining human rights.

The vote could, however, provide legitimacy for Maduro to offer investment deals to the few companies around the world willing to risk running foul of Washington's sanctions for access to the world's largest oil reserves.

The election closes a cycle that began in 2015 when the opposition won congress by a landslide, only to see their legislative powers swept aside by pro-government courts and the creation in 2017 of an all-powerful body known as the National Constituent Assembly.

Guaido, head of the current congress, had said Venezuelans should skip the vote and participate in a Dec. 12 consultation that will ask citizens whether they reject Sunday's vote and want a change of government.

Guaido and his overseas allies said the Maduro government did not meet conditions to hold a fair election.

The pro-government supreme court handed key opposition parties to politicians who were expelled from those parties on suspicion of being in league with Maduro. The electoral board was named without the opposition's participation, and Maduro refused to allow for meaningful electoral observation.