President Evo Morales forcefully defended the nationalization of Bolivia's petroleum industry only hours after the Senate voted to censure the nation's Hydrocarbons Minister over alleged "irregular" dealings by the state energy company.

"Nationalization will not stop," the Morales said Wednesday night, calling conservative legislators who voted to censure the minister in charge of the process, Andres Soliz, were "traitors and murderers" who "won't allow politics to change in out country."

Opposition members of the Bolivian Senate also voted to open an investigation into the dealings of Jorge Alvarado, head state petroleum company Yacimientos Petroliferos Fiscales Bolivianos, YPFB.

Senators from Morales' own party Movement Toward Socialism boycotted the session.

Soliz immediately submitted a letter of resignation, writing that the vote against him came from "those who wish that Bolivia would return to a state of semi-colonization by world powers allied with the oligarchies who have exploited our people for 500 years."

Appearing on national television in his trademark blue-and-red striped sweater, Morales passionately refused to accept Soliz' resignation, declaring "solidarity, support and respect" for "one of my best ministers."

Morales nationalized Bolivia's oil and gas industry on May 1, seizing the property of foreign energy companies and giving them six months to cede operational control to YPFB or leave the country.

Earlier this month Bolivia announced that the "full effect" of nationalization would be suspended while YPFB underwent a complete reorganization and sought US$180 million (euro140.5 million) in emergency financing.

Soliz was called before the Senate opposition leaders last week to answer questions on the slow progress of nationalization. The minister acknowledged that the process has lagged.

The Bolivian government admitted on Monday that Alvarado, who answers directly to Soliz, had violated the terms of nationalization by entering YPFB into contract with an independent export firm.

According to Morales' May 1 decree, the state angry company is required to assume control of every stage of the production process.

However, critics say YPFB lacks the resources or technical know-how to manage Bolivia's natural gas reserves.

Meanwhile, Morales' opponents argue that nationalization has amounted to little more than a political show.

"Nationalization is just talk," said Samuel Doria Medina, leader of the opposition party National Unity. "115 days have passed and there is not a single new contract."