Bolivian President Evo Morales has ordered a U.S. diplomat out of the country in the second such expulsion since September.
The president on Monday declared Francisco Martinez persona non grata, accusing Martinez of involvement in a "conspiracy" against the Bolivian government.
Last month, Bolivia's government accused Martinez of working with a former Bolivian police officer who, it alleged, infiltrated the state-run energy company YPFB on behalf of the U.S. Central Intelligence Agency.
The French news agency, AFP Monday quoted Mr. Morales as alleging that Martinez was "in permanent contact with opposition groups during the entire period of the conspiracy," which, the president claimed, caused Bolivia's anti-government unrest in September 2008.
The State Department called the expulsion order "unwarranted and unjustified." Martinez has served as second secretary at the U.S. Embassy in La Paz.
Last month, a spokeswoman for the U.S. Embassy in the Bolivian capital described as "false accusations" Mr. Morales' claims about a U.S. conspiracy.
This past September, the Bolivian president expelled the U.S. ambassador, Philip Goldberg, blaming him for inciting violent anti-government protests. The U.S. State Department called Goldberg's expulsion a "grave error" and dismissed the accusation as "baseless."
Last year, President Morales also ordered the U.S. Drug Enforcement Administration to cease operations in Bolivia, accusing DEA agents of spying and supporting anti-government protests. U.S. officials rejected those accusations as well.
Some information for this report was provided by AFP, AP and Reuters.