President Morales held up a coca leaf at his news conference
Bolivian President Evo Morales has ordered the expulsion of a US diplomat he accused last week of colluding with opposition groups in recent unrest.
He said Francisco Martinez, a political officer at the US embassy in La Paz, had links to groups involved in violent opposition protests.
President Morales ordered the US ambassador to leave the country six months ago over similar allegations.
The US government has denied the latest allegations as baseless.
Since his election in 2006, Bolivia's first indigenous president, a leftist who came to national prominence as a leader of the country's coca farmers, has frequently accused Washington of meddling.
He accused the CIA of conspiring against his energy policies two weeks ago, and in November he suspended all co-operation with the US Drug Enforcement Administration over allegations of collusion with the opposition.
"Today, I've decided to declare Francisco Martinez... persona non grata," he told a news conference in La Paz, the country's administrative capital.
"Deep investigations" had determined that the US embassy's second secretary had been "in permanent contact with opposition groups".
The expulsion was, he said, a move to "put an end to a foreign conspiracy".
Mr Morales publicly accused the US diplomat last week of "co-ordinating contacts" with a Bolivian police officer he accused of infiltrating the state oil company YPFB on behalf of the CIA.
The head of YPFB, Morales ally Santos Ramirez, was arrested last month amid corruption allegations.
Denying CIA involvement, Washington accused the Bolivian president last week of using the US as a scapegoat in domestic politics.
"We can't understand how the president can assure us that he wants better relations with the United States and at the same time continue to make false accusations," said US embassy spokeswoman Denise Urs.
In September, Mr Morales expelled US ambassador Philip Goldberg for "conspiring against democracy" and encouraging Bolivia's break-up.
The US also described those allegations as unfounded.