The Spanish government said Sunday it regretted the decision by Bolivia to nationalise units of Spain's Iberdrola utility group and stressed the importance of "legal security" for foreign investors.
"Legal security is a crucial requirement for all foreign investment in Bolivia," Industry Minister Jose Manuel Soria told ABC newspaper.
"I regret this decision, which was taken without notifying Spanish authorities who were surprised by the measures," Soria said.
Late Friday the foreign ministry issued a statement also regretting Bolivia's move.
Bolivia nationalised electric utilities owned by Iberdrola on Saturday, sending police and troops to enforce the latest expropriation ordered by the populist leader of South America's poorest nation.
President Evo Morales announced a decree targeting Iberdrola-owned utilities Electropaz and Elfeo in the cities of La Paz and Oruro.
In La Paz, soldiers later took control of power plants that until now were run by Iberdrola, while police seized corporate offices.
Iberdrola said it hopes Bolivia will pay "a fair price" for the utilities nationalised by La Paz.
Morales said he was acting because Iberdrola charged more for electricity in rural areas than it did in cities, and service was also uneven.