Alvaro Uribe made the disclosure on Saturday at Santa Marta in Colombia, where he is meeting President Chavez, and after analysing documents furnished by the Venezuelan leader.
He said: "The Venezuelan soldiers who are in Bogota went to a building to meet with members of the Colombian military. President Chavez gave us these documents ... we analysed them and this morning I said to President Chavez, 'I must tell you the truth: this is a building of Colombia's public forces.'"
Uribe said that intelligence efforts against the Venezuelan government were conducted in the building, and took full responsibility for the affair.
The two presidents met on Saturday for six hours in a climate of unusual goodwill to discuss the purported Bogota-based conspiracy against the Venezuelan president, which Chavez first disclosed to the Colombian president during a meeting in Venezuela last month.
Seven Venezuelans involved in a 48-hour coup against Chavez in April 2002 have been linked to the new plot.
Pedro Carmona, a businessman and leader of the failed military-civilian coup, enjoys political asylum in Colombia, where he is working as a university professor.
Uribe refused asylum to six Venezuelan soldiers involved in the coup, but gave them permission to live in Colombia while they look for safe haven in another country.
The conservative Colombian leader said on Saturday that he took responsibility for the events.
"I took responsibility before President Chavez and I took it in public, because the government of Colombia, which suffers from terrorism, cannot permit anyone to plot conspiracies, especially against a brother country," he said.
Chavez said he supported any
Colombian peace process
Chavez, a leftist, in turn stressed that he would support any Colombian peace process, in an apparent effort to counter allegations by critics that he supports leftist Colombian rebels.
"I beg Colombians not to believe any of that, because it is a lie," he said. "We support Colombia's institutions, we support President Uribe, we support whatever the people of Colombia decide, we support Colombian democracy and we want armed groups to embrace peace."
On Tuesday, Edgardo Maya, Colombia's attorney-general, said no charges had been filed in relation to the alleged plot.
Maya said: "The attorney-general's office has no information about it. International relations are handled strictly by the president of the republic."