The 15 tons of materials seized last week in northern Honduras were intended for the production of synthetic drugs and were not cocaine, officials said.

Lab tests conducted on Saturday indicate that the substance is an "amphetamine derivative used to produce synthetic drugs," prosecutor's office spokesman Melvin Duarte told Efe.

The substance was found last Thursday in Pata de Gallina, a village in Yoro province.

More may be known on Sunday about the materials, which were seized in an area of Honduras where South American drug traffickers operate, Duarte said.

The substance was found in a tunnel that also housed "chemical products, an electrical system and a transformer," prosecutor's office spokesman Carlos Vallecillo told Efe last week.

The security forces seized more than 22 tons of cocaine in operations staged in 2011, with U.S. drug enforcement agents taking part in some of the raids, officials said. EFE