Bolivia has nationalised a major oil and gas pipeline company that had been owned by Anglo-Dutch energy giant Royal Dutch Shell and Ashmore Energy International, a US firm.
Evo Morales, the Bolivian president, signed a decree giving the government full ownership of Transredes SA, which transports natural gas to Brazil and Argentina.
Morales said he had held talks with Ashmore executives, but they had failed to reach a deal.
"We waited patiently all month, but the actions they took were totally different," Morales said at a signing ceremony in the eastern city of Santa Cruz on Monday.
"They wanted to be bosses, and have us be the employees. Partners are welcome, but we will not accept bosses."
Morales also accused Transredes of "having conspired" against his government.
The two foreign companies declined to comment on the announcement.
Since his election as Bolivia's first indigenous president in 2005, Morales has moved to exert greater state control over the country's natural gas fields - the second largest in South America, after Venezuela's.
Energy industry analysts have said that YPFB, or Yacimientos Petroliferos Fiscales Bolivianos, the state oil company, may lack the technical expertise to handle its growing role the country's gas distribution system.