An official with Mexico's state-run oil company says a proposed energy reform could make it easier for Petroleos Mexicanos to create subsidiaries to exploit the country's vast shale oil and gas reserves.

Production and exploration director Carlos Morales says the company has only started to explore shale reserves that could more than double daily gas output. Mexico currently has to import gas to meet demands. He said shale exploration is not run by large oil companies such as Pemex, as it's known, rather by small specialty operations.

Morales said Thursday that companies working in shale reserves "no doubt" would need licenses or concessions to make the ventures worthwhile, arrangements that are forbidden by the constitution.

A controversial reform that would open up Mexico's moribund oil industry is pending before congress.