BOGOTA (Reuters) - Colombia said on Wednesday it had sent a letter of protest to Caracas after Venezuelan soldiers entered its territory last week, the latest in a series of unauthorized crossings.

Unapproved entrances to Colombia by the Venezuelan military along the two countries’ porous border occur regularly. Colombia’s right-wing President Ivan Duque frequently spars with Venezuelan President Nicolas Maduro, whom Duque calls a dictator.

Armed members of the Venezuelan National Guard entered the Pica del Dos area of Tibu municipality on Nov. 1, the foreign ministry said in a statement, without elaborating.

“There was a violation of national territory,” it said. “The Foreign Ministry, in the name of the Colombian government, has sent a letter of protest denouncing the repetition of these violations of sovereignty.”

Venezuela’s socialist government did not immediately respond to a request for comment.

Three Venezuelan soldiers died in an attack by an armed group in the southern border province of Amazonas last week.

Colombia is the top destination for Venezuelans fleeing food and medicine shortages during their country’s deep economic crisis.