Uruguay's president Jose Mujica, speaking without realising a microphone was on, has said Argentinian president Cristina Fernandez de Kirchner is "worse" than her late husband and predecessor, Nestor Kirchner.
"This old hag is worse than the cross-eyed man," Mr Mujica (77) said at an event in Uruguay last night, according to a video posted on Todo Noticias Television channel website and audio posted on Uruguay's El Observador. "He was more of a politician, she's stubborn."
Relations between the neighbouring countries have deteriorated since Argentina restricted imports and tightened controls on the exchange market. The measures, which limit access to foreign currencies, have hurt Uruguay's exports and tourism industry.
A $1.1 billion investment by Finland's Metsae-Botnia Oy in a pulp mill on the river bordering both countries led to a four-year bridge blockade by Argentina, which accused Uruguay of violating an international accord on the river's use.
In 2007, when then Uruguayan president Tabare Vazquez allowed the pulp mill to start operations, Nestor Kirchner told him that he had "stabbed Argentina in the back".
In 2002, Uruguayan president Jorge Batlle accused Argentines of being a "bunch of thieves", a comment for which he later apologised during a trip to Buenos Aires.
Mr Mujica, a former paramilitary who took office in 2010, said later he didn't publicly speak about Argentina at the event in Uruguay and will not offer clarifications, according to Montevideo-based newspaper El Pais.
Argentine foreign minister Hector Timerman said the comments were "unacceptable" "denigrating" and "offensive" to the memory of the deceased Mr Kirchner, according to a statement addressed to Uruguay's ambassador in Argentina. Ms Kirchner will not be responding to the insults, Mr Timerman said in the statement.
Mr Kirchner, who died in October 2010 from a heart attack, was president from 2003 to 2007. His wife succeeded him and was re- elected in 2011.
Mr Mujica traveled to Caracas for former Venezuelan president Hugo Chavez's funeral last month on her plane.