CARACAS (AFP) - Venezuelan opposition leader Henrique Capriles vowed on Sunday to "take to the world" his challenge of this month's presidential vote, as election officials readied a partial ballot recount.

Mr Capriles, who says he should have been declared the winner of the April 14 presidential vote, alleged via his Twitter account that election authorities rejected his appeal for a full recount "at the order of the Socialist Party" that governs Venezuela.

Election officials said they plan to begin a partial vote recount on Monday as they probe for election irregularities.

Venezuela's National Electoral Board has said that a full vote recount is legally impossible, but Mr Capriles rejects anything less as insufficient, and vowed in a tweet that "sooner or later, there will be new elections."

A group of opposition lawmakers who back Mr Capriles's challenge said they too would continue to draw attention to the case, including launching appeals at regional bodies like Mercosur and Unasur.

"We will go to all the (global) organisations, so that the whole world knows that Henrique Capriles Radonski won the elections in Venezuela," said opposition lawmaker Ismael Garcia.

Mr Capriles narrowly lost the presidential election to Mr Nicolas Maduro, political heir to late president Hugo Chavez, who died last month. Mr Maduro has since been sworn in as president.

The margin of victory was just 1.8 per cent, according to election officials.

Mr Capriles - a businessman, lawyer and former Miranda state governor - alleges that some voters cast multiple ballots or even used ballots belonging to people who had died.

He has vowed to resort to the court system if necessary to get a vote recount, saying that the only acceptable election audit is one that examines all voters' signatures and fingerprints.

Both the government and Mr Capriles have urged their supporters to turn out for massive street protests planned for May 1.