Bolivian President Evo Morales signed a decree Monday on nationalizing the country's natural gas and petrol industry, which has drawn "deep concern" from foreign investors in the country.

At a signing ceremony in Yacuiba in the southern department of Tarija, which has 85 percent of Bolivia's natural gas, Morales said the government "keeps its electoral promises... and from this moment, the looting of our natural resources by foreign companies will end," according to reports from the Bolivian capital of La Paz.

Morales added that the army was ordered to occupy natural gas fields to enforce compliance.

"We want... the armed forces... starting now... to occupy the country's energy fields with battalions of engineers," said the president.

The move was a surprise because the Bolivian government had said in recent days that Bolivia was still in the process of preparing the decree.

Soldiers and engineers with Bolivia's state oil company YPFB were sent to installations and fields controlled by foreign companies, which have six months to agree to new contracts or leave the country.

About 100 armed soldiers took control of a gas refinery in the eastern city of Santa Cruz on Monday afternoon. Some of the soldiers carried machine guns, while others carried anti-riot gear.

Bolivian Vice President Alvaro Garcia said troops were sent to 56 locations around the country as soon as Morales signed the decree.

Under the decree, the YPFB will control all natural gas fields in Bolivia and pay foreign companies for their services.

Some operators will get about 50 percent of the value of gas they extract, but Bolivia's two largest gas fields insist on giving their operators only 18 percent of the revenue of gas extracted there.

Bolivia has a reserve of about 48.8 trillion cubic feet of natural gas, the second largest deposit in South America, which is being exploited by about 20 foreign firms, including Brazil's government-run oil company Petrobras, Britain's BG Group PLC, France's Total, and Spanish-Argentine Repsol-YPF.

Morales, who took office in January as Bolivia's first Indian president, has repeatedly said his country's natural resources must be nationalized so that Bolivians could benefit from the profits that were sent overseas.

In Madrid, the Spanish government said in a statement that Spain is "deeply worried" by Bolivia's decision.

"The (Spanish) government hopes that during the time given to companies to regularize their current contracts, there will be a process of genuine negotiation and dialogue between the government and companies," said the statement released by the Foreign Ministry.

It also called for respect for the interests of each party to "avoid sending a negative signal to the international investor community which is following the developments closely."

Spain would continue to work with Bolivia and the two countries would maintain "intensely close" relations, so that a solution satisfying all parties can be reached, said the statement.

Also on Monday, Brazilian Mines and Energy Minister Silas Rondeau said Bolivia's nationalization of its oil and gas industry was an "unfriendly" move.

"It is an unfriendly move that could be understood as a break with understanding made with the Bolivian government," Rondeau told Folha news.

Meanwhile, Jose Sergio Gabrielli, president of Petrobras, also criticized the decree signed by Morales.

"Evo Morales' decree was a unilateral measure adopted in an unfriendly way," Gabrielli told the official Brazilian news service Agencia Brasil in the U.S. city of Houston, where he was taking part in an international oil conference. "It obliges us to analyze very carefully our situation in the country."

"Petrobras will take all the necessary measures, at all levels, to guarantee its rights," he added.

Petrobras, a top investor in Bolivia, controls 14.5 percent of Bolivia's gas reserves and has invested millions in Bolivia since 1996.

Source: Xinhua