Ecuador today will begin imposing stiff tariffs on hundreds of Colombian imports, the latest round in a festering dispute between the neighbors.

The tariffs could affect at least one-third of the $1.6 billon in annual Colombian exports to Ecuador. The Ecuadorean government said the measure was put in place to compensate for a recent devaluation of the Colombian peso.

But observers say there is little doubt that it is the latest in a series of retaliatory measures by both countries since Colombia sparked a regional crisis with its brief incursion into Ecuadorean territory in March 2008 to kill a high-ranking leftist rebel leader.

Ecuador's move follows the unusual filing of murder charges last month by a local judge against former Colombian Defense Minister Juan Manuel Santos, who planned the incursion last year that left more than 20 people dead in addition to Raul Reyes, a leader of the Revolutionary Armed Forces of Colombia, or FARC.

The Ecuadorean government subsequently signaled its approval of the charges by requesting that Interpol issue a "red notice" for Santos to authorize his arrest by foreign countries. Interpol turned down the request last week, but Colombia signaled that it was offended by Ecuador's actions.

Last week, Colombian President Alvaro Uribe accused Ecuador of harboring terrorists. "This is nothing but a pirouette by abettors of a torturing, criminal, cynical and sadist group that is the FARC," he said, reacting to Ecuador's Interpol request.

Ecuador's president, Rafael Correa, responded by accusing Uribe of sponsoring right-wing paramilitary groups, also classified as terrorists by the U.S. State Department.

Colombia then struck back by filing a suit in the International Criminal Court accusing Correa, ex-Interior Minister Gustavo Larrea and ministry official Ignacio Chauvin of links with the FARC.

Some investigators say evidence from laptops seized in Reyes' camp after the raid about a mile south of the Colombian border indicates that the FARC had extensive contact with Ecuadorean officials. Others however, say that it was impossible to prove the data on the laptaps was not "planted" after the attack.