Ecuadorean authorities arrested former Vice President Jorge Glas on Friday evening, seizing him from the Mexican embassy and prompting Mexico to suspend bilateral relations.
Glas, convicted twice for corruption, had been holed up in the embassy in Quito since seeking political asylum in December, a request Mexico granted earlier on Friday.
Police forcefully entered Mexico's embassy in Quito before making the arrest, Mexican President Andres Manuel Lopez Obrador posted on X.
The Ecuadorean president's office said in a statement it had arrested Glas, who was vice president under the leftist government of Rafael Correa between 2013 and 2017.
There was a heavy military presence at the magistrates court in the Andean capital, where the former vice president was taken.
The arrest caps a week of escalating tensions between Mexico and Ecuador, which on Thursday declared Mexico's ambassador in Quito persona non grata, citing "unfortunate" comments from the leftist President Lopez Obrador.
Ecuador contends that Mexico's asylum offer was illegal.
In a statement, Ecuador's presidency accused Mexico of "having abused the immunities and privileges granted to the diplomatic mission that housed the former vice president, and granting diplomatic asylum contrary to the conventional legal framework."
Lopez Obrador said he had instructed Mexican Foreign Minister Alicia Barcena to suspend diplomatic ties with Ecuador, calling the arrest an "authoritarian" act and a violation of international law and Mexican sovereignty.
Barcena announced the "immediate" suspension of diplomatic ties with the South American nation shortly afterward on X.
Ecuadorean authorities had sought permission from Mexico to enter the embassy and arrest Glas, who was sentenced to six years in prison in 2017 after he was found guilty of receiving bribes from Brazilian construction firm Odebrecht in exchange for awarding it government contracts.
Glas, who has a preventive arrest warrant out on another corruption case, has complained that he is being persecuted for his political affiliation, which Ecuador's government denies.
Ecuadorean officials this week were angered by Lopez Obrador's comments on the South American country's bloody elections last year, in which a presidential candidate was assassinated.
Ecuadorean President Daniel Noboa took office late last year and quickly faced an escalating conflict with drug gangs, which prompted him to declare a nationwide state of emergency early this year, which he extended last month.