Cross-border raids into western Ivory Coast have become more violent and better organized, and could have profound effects on security in the region near Liberia if they continue, a United Nations expert panel warned in a report.

The U.N. experts said the attacks are believed to have been orchestrated by supporters of former Ivory Coast President Laurent Gbagbo, who refused to step down after losing the November 2010 election to now-President Alassane Ouattara. The months-long crisis sparked postelection violence that claimed at least 3,000 lives.

As of September, more than 60,000 Ivorians who fled the crisis remained in Liberia, including hundreds of pro-Gbagbo militiamen, according to U.N. figures.

The attacks date back to July 2011 and include a raid in June 2012 that killed seven U.N. peacekeepers and at least 10 civilians. The most recent border strike came in August, at the height of a series of attacks on military installations throughout Ivory Coast that sparked fears of renewed unrest in the world's biggest cocoa producer.

The new report published Thursday from the U.N. Panel of Experts on Liberia, which monitors sanctions against the country, said that there have not been successful prosecutions despite a military operation launched by Liberia in June to target the individuals involved in the attacks.

On the contrary, "most leading combatant commanders who had previously been imprisoned" have been set free, and "Ivorian commanders in particular have avoided detection and recriminations," the report said.

Information from October also revealed preparations for attacks to be launched from Liberia's Grand Gedeh and Nimba counties, the report said. The experts could not independently substantiate these claims, but noted that they had received similar information prior to the June attack that killed the peacekeepers and an earlier attack on the Ivory Coast town of Sakre.

High unemployment in eastern Liberia plays into militia leaders' recruitment efforts, according to the report, especially as Ivorian refugees can't get jobs and "have limited means to participate in the informal economy," it said.

While attacks have begun to target Ivory Coast's army and "exhibit tactical dimensions," more strategic efforts "have failed at the planning stage or have not been attempted," the report said. It said the combatants operate as a collection of "gangs" affiliated by ethnic group and financed by supporters in nearby countries.

"The fact that networks inside Liberia lack hierarchical structure could be symptomatic of a lack of coordination at the strategic level," including among high-level Gbagbo allies currently exiled in Ghana, the report said.

An October report from U.N. experts on Ivory Coast also pointed to the role that Gbagbo allies based in Ghana have allegedly played in orchestrating the cross-border raids. Ivorian authorities have expressed frustration that Ghana has not executed arrest warrants for Gbagbo allies suspected of coordinating the recent violence.