Venezuela on Tuesday stepped up security and closed its borders earlier than usual ahead of Sunday s presidential election after acting President Nicolas Maduro claimed former US officials hatched a plot to kill him.

Interior Minister Nestor Reverol said a "strict control" of movements was imposed along land borders with Colombia and Brazil that will last until 1030 GMT on Monday, one day after the election to replace late leader Hugo Chavez.The government usually shuts down the borders closer to election day. In last October s presidential election between Chavez and opposition leader Henrique Capriles, the borders were closed a day before the vote.

Reverol said the measures were imposed after intelligence services found "elements that generate violence who hope to use our territory s border to create a climate of destabilization."Maduro, who is favored to win this weekend s election against Capriles, claimed last week that Salvadoran hitmen had entered the country as part of a plot backed by two former US officials and El Salvador s right-wing to assassinate him.

Reverol said operations would be launched "in the coming hours" to catch the suspects.Salvadoran President Mauricio Funes ordered an investigation into whether right-wing lawmaker Roberto D Aubuisson was involved in the plot. D Aubuisson has dubbed the claim "a lie."On election day, the Venezuelan interior minister said, some 125,000 security forces will operate under a "special security and patrol plan" in more than 13,600 polling stations.

Security was reinforced at power stations and telephone lines as well as underwater fiber optic cables to prevent any "sabotage" during the election, Reverol said.Authorities said 17 people, including employees of the state-run National Electricty Corp., were caught sabotaging the power system to create blackouts. Maduro has claimed that the opposition was planning to shut down the national power to disrupt the election.

Earlier in the day, Maduro and Capriles signed separate pledges to recognize the election results.Addressing thousands of government workers in front of the Miraflores presidential palace, Maduro used a red pen to put his signature on a document drafted by the National Electoral Council at his request."I will respect the results that the people decide on Sunday, April 14. I swear before God, I swear before the people, I swear in the memory of Hugo Chavez," the late leader s chosen successor said.

Capriles, who signed a similar pledge before he lost the October 7 presidential election to Chavez, put his signature on a different document during a rally in northeastern Venezuela.The opposition has accused the electoral council of being biased towards the acting president s campaign and failing to censor it for using state resources for Maduro s candidacy.