BOGOTA, Colombia (AP) — The office of Colombia's chief prosecutor says authorities are opening an investigation into whether an Alabama-based coal company financed a paramilitary group during the South American nation's bloody civil conflict.

The investigation into Drummond Ltd. is expected to focus on irregular payments allegedly made to a contractor already found guilty in the murders of two labor leaders.

Accusations have long swirled that Drummond financed an umbrella paramilitary group but those claims have repeatedly been dismissed in U.S. courts.

In a statement Tuesday, Drummond said it has never supported illegal armed groups.

A rights lawyer called the investigation's opening a "first step" toward justice for relatives of those killed by the right-wing militia during the conflict.