Twenty-three people have been reported killed so far in Colombia's Arauca province amid fighting between illegal armed groups, Defense Minister Diego Molano told a news conference late on Monday.
Fighting broke out over the weekend in Arauca - which sits on the border with Venezuela - as members of the National Liberation Army (ELN) fought with dissidents of the Revolutionary Armed Forces of Colombia (FARC), who reject a 2016 peace deal.
The groups were fighting over control of illegal economies such as drug trafficking, Colombia's army said in a statement late on Sunday. The violence also displaced 12 families, Colombia's human rights ombudsman said.
The violence harks back to the mid 2000s, when the FARC and ELN fought each other in Arauca and the neighboring Venezuelan state of Apure.
By the time fighting ceased in 2010, more than 58,000 people had been displaced in the province and at least 868 civilians had been killed, according to a report from advocacy group Human Rights Watch (HRW), which cited the government-run Colombian Victims' Unit.
Some 5,000 people fled Apure at the end of March last year amid clashes between Colombian armed groups and the Venezuelan military.
HRW received reports of 24 deaths due to the violence, the group's senior investigator for the Americas Juan Pappier said in a message on Twitter, adding that there had also been forced displacements and kidnappings.
"We are very concerned about the fighting between the ELN and dissidents of the FARC's 10th front in Arauca and Apure," Pappier said.
Colombia's President Ivan Duque convened a meeting of military and police leaders to assess the situation in Arauca and to take measures to address it.
"I have ordered that two battalions be deployed within the next 72 hours to help with the task of territorial control," Duque said in a video broadcast, while accusing Venezuela of sheltering FARC dissidents and the ELN.
Venezuelan Defense Minister General Vladimir Padrino ridiculed the accusations on Twitter. Venezuelan military forces stationed in border municipalities have raised their level of alert in response to the fighting in Colombia, he added.