Police stormed the Mexican embassy in the Ecuadorian capital of Quito on Friday to seize the former Ecuadorian vice president Jorge Glas.
Mr Glas was taking refuge in the embassy.
Mexican President Andres Manuel Lopez Obrador declared the act “a flagrant violation of international law and the sovereignty of Mexico”.
He added that as a result of Ecuador’s actions, Mexico will officially sever diplomatic relations with its neighbour.
The raid took place hours after the Mexican government granted Mr Glas political asylum, as diplomatic tensions between the two countries deepened.
Mr Glas is perhaps the most wanted man in Ecuador and faces investigations into corruption, bribery and more.
The police broke the external doors of the Mexican diplomatic headquarters in the Ecuadorian capital and entered the main patio.
Ecuador’s presidency issued a statement on Friday: “Ecuador is a sovereign nation and we are not going to permit any criminal to stay free.”
Mr Lopez Obrador fired back, dubbing the intrusion an “authoritarian act”.
He wrote on X, formerly Twitter, that his government will “proceed legally and immediately declare the suspension of diplomatic relations”.
Experts watching the arrests pointed out that the act was a bold violation of the Vienna Conventions on Consular Relations, which is likely to drive a wedge between the governments of Mexico and Ecuador.
“This is not possible, it cannot be, this is crazy,” said Roberto Canseco, head of the Mexican consular section in Quito, outside the embassy.
Asked about the situation of the former vice president and if he was apprehended by public forces, he stated: “I understand that yes, I am very worried because they could kill him; there is no basis to do this, this is totally outside the norm.”
The Mexican embassy in Quito remained under heavy police guard late on Friday.
A day earlier, tensions between the two countries escalated after Mr Lopez Obrador made statements that Ecuador considered “very unfortunate” about the last elections in which the Ecuadorian president Daniel Noboa won.
In reaction, the Ecuadorian government declared the Mexican ambassador persona non grata.
On Saturday, Mr Glas was taken by armoured vehicle from the attorney general’s office to an airport, where he boarded a plane for a flight to the port city of Guayaquil, 265 miles (425km) south of Quito.
People who had gathered outside the prosecutor’s office yelled “strength” as the convoy of police and military vehicles moved off.
Ecuador’s corrections agency said Mr Glas will remain in custody at a maximum-security facility in Guayaquil.
Authorities are investigating Mr Glas over alleged irregularities during his management of reconstruction efforts following a powerful earthquake in 2016 that killed hundreds of people. He was convicted on bribery and corruption charges in other cases.
Alicia Barcena, Mexico’s secretary of foreign relations, posted on X, formerly Twitter, that a number of diplomats suffered injuries during the break-in, adding that it violated the Vienna Convention on Diplomatic Relations.
Diplomatic premises are considered “inviolable” under the Vienna treaties and local law enforcement agencies are not allowed to enter without the permission of the ambassador.
Ecuador’s Foreign Minister Gabriela Sommerfeld on Saturday told reporters that the decision to enter the embassy was made by President Daniel Noboa after considering Glas’ “imminent flight risk” and exhausting all possibilities for diplomatic dialogue with Mexico.
Mexico granted Glas asylum hours before the raid. Ms Sommerfeld said “it is not legal to grant asylum to people convicted of common crimes and by competent courts.”
Alicia Bárcena, Mexico’s secretary of foreign relations, on Friday posted on X that a number of diplomats suffered injuries during the break-in, which she said violated the Vienna Convention on Diplomatic Relations. Ms Sommerfeld did not address the injury claims.
People seeking asylum have lived anywhere from days to years living at embassies around the world, including at Ecuador’s in London, which housed WikiLeaks founder Julian Assange for seven years because British police could not enter to arrest him.
The decision of Ecuadorian authorities was condemned by presidents, diplomats and a regional body on Saturday.
Honduran President Xiomara Castro, writing on X, characterised the raid as “an intolerable act for the international community” and a “violation of the sovereignty of the Mexican State and international law” because “it ignores the historical and fundamental right to asylum”.
The Organisation of American States in a statement reminded its members, which include Ecuador and Mexico, of their “obligation” to not “invoke norms of domestic law to justify non-compliance with their international obligations”.
“In this context, it (the OAS) expresses solidarity with those who were victims of the inappropriate actions that affected the Mexican Embassy in Ecuador,” according to the statement released Saturday.
The organisation added that it deemed a meeting of its permanent council “necessary to address the issue,” but did not set a date.
Ms Barcena on Friday said Mexico would take the case to the International Court of Justice “to denounce Ecuador’s responsibility for violations of international law”.
Mr Noboa became Ecuador’s president last year as the nation battled unprecedented crime tied to drug trafficking.
After a group of armed individuals assaulted a TV station during a live broadcast in January, he declared the country in an “internal armed conflict” and designated 20 drug-trafficking gangs as terrorist groups that the military had authorisation to “neutralise” within the bounds of international humanitarian law.
Ecuador’s ministries of foreign affairs and interior did not respond to multiple requests for comment from The Associated Press.
Former Ecuadorian ambassador Jorge Icaza told AP that the raid was illegal, but he added that it is also against the law to protect “a criminal who was punished by the Ecuadorian justice system in two prominent cases, which is also negative from the point of view of international norms”.
