President Hugo Chavez's governing party won full control of the 167-National Assembly, claiming a sweeping victory in congressional elections boycotted by major opposition parties.

Official results of Sunday's election were still being tallied Monday, but leading lawmaker Willian Lara said candidates of Chavez's Fifth Republic Movement party had won 114 seats. Including allies from other parties, the entire 167-member chamber could be filled with pro-Chavez lawmakers, he said.

A two-thirds majority would allow pro-Chavez lawmakers to amend the constitution, and some lawmakers have said they would consider a reform to extend term limits for all offices, including the president. Chavez has already served nearly seven years.

Five major opposition parties pulled out of the race, complaining they did not trust the electoral system. Chavez dismissed the boycott as a failed ploy to sabotage legitimate elections and avoid defeat.

Polls indicated the ruling party would trounce the opposition.

"The whole world knows a true democracy is in motion here in Venezuela," Chavez said.

The president has accused the United States., with which he often clashes, of being behind the boycott — a charge Washington has denied.

Caravans of Chavez supporters drove through the streets honking horns in celebration.

Officials said government foes tried to disrupt the vote by blowing up an oil pipeline. They called the pipeline explosion Saturday night a failed plot aimed at paralyzing supplies to Venezuela's largest oil refinery and destabilizing the country.

Thousands of soldiers were deployed to keep order during the vote, and there were no major reports of violence.

Maria Corina Machado, who leads the U.S.-backed vote watchdog group Sumate, called the vote "illegitimate."

"We are going to have a single party parliament that doesn't represent ample sectors of society," she said in a statement.

Government officials say the U.S. meddled in the elections through Sumate, which receives money from the Washington-based National Endowment for Democracy, a private group funded by the U.S. Congress.

Venezuelan Foreign Minister Ali Rodriguez has called Sumate leaders "mercenaries of the U.S. government."

Officials reported several disturbances leading up to the vote, including blasts from small explosives that injured three in Caracas on Friday and the pipeline explosion Saturday in the western state of Zulia.

Oil Minister Rafael Ramirez blamed the opposition, saying those responsible for the pipeline attack were the same people behind a crippling two-month oil strike aimed at ousting Chavez that ended in 2003. Nobody was hurt in the explosion, and Ramirez said the refinery has enough inventories to cover supply needs.

"We already know who is behind this situation, and we have made some arrests," Interior Minister Jesse Chacon said, saying authorities found traces of explosives on the pipeline.

The military said it stepped up security at oil installations in the country, the world's No. 5 oil exporter.

Candidates allied with Chavez held 89 seats before the election in the 165-seat National Assembly, which is being expanded to 167 members.

The boycotting parties argue the National Electoral Council is pro-Chavez and expressed concerns about the voter registry and touchscreen voting machines. Elections officials denied any problems, saying they made many concessions for the opposition.

The Organization of American States had 60 observers monitoring the vote, while the European Union had 160 observers on hand.