Federal prosecutors on Friday charged three West Africans with plotting to transport tons of cocaine across Africa in concert with Al Qaeda, using for the first time against that group a 2006 law aimed at drug trafficking that aids terrorism.

Federal officials say the case promises to peel back what they contend are increasing ties between drug traffickers and Al Qaeda as the terrorist group seeks to finance its operations in Africa and elsewhere. The case focused on a criminal organization in Ghana and elsewhere in West Africa that investigators believe worked with Al Qaeda, moving drugs to North Africa and on to Europe.

The case was based in some measure on the work of two informants, paid by the federal Drug Enforcement Administration, who posed as representatives of the Revolutionary Armed Forces of Colombia, or FARC, a Colombian rebel group that has taken advantage of lax enforcement and corruption to use Africa as a significant transshipment route to Europe. As part of the investigation, one of the informants approached the defendants, according to the complaint, saying he was seeking help in setting up a network to smuggle cocaine across the continent.

Over the course of the four-month investigation, federal drug agents secretly recorded and videotaped the three West African men, who said they were associated with Al Qaeda and had transported drugs and provided support to the group in the past. Federal law enforcement officials, however, said the inquiry had uncovered no independent evidence that corroborated their statements.