Spain is "deeply worried" by a decree signed by Bolivian President Evo Morales ordering total state control of the country's natural gas fields, a government statement said on Monday.

"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.

Spanish-Argentine energy company Repsol-YPF is one of the largest investors in Bolivia.

According to a decree signed by Morales earlier in the day, Bolivia's state oil company YPFB will control all natural gas fields and pay foreign companies for their services.

Some operators will get about 50 percent of the value of gas they extract, but 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.

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.

Source: Xinhua