The Basel Action Network, or BAN, should report the alleged irregularities that occurred in the sale of two ships by state-owned oil giant Petroleos Mexicanos, or Pemex, to scrap yards in Pakistan and Bangladesh, the Mexican Environment Secretariat said.

"The Environment and Natural Resources Secretariat calls on this NGO to go before the appropriate agencies and make them aware of the countries on whose territory conduct that could be considered contrary to applicable laws occurred," the secretariat said in a statement.

The U.S.-based environmental group alleged last week that Pemex sold two ships to salvage yards in Asia that contained hazardous materials, a violation of both Mexican and international law.

"The arrival of these obsolete vessels, the Sebastian and the De Marz, in South Asia without notice and without first being pre-cleaned of the tons of hazardous materials built into each ship is a clear violation of the UN Basel Convention and Mexican law," BAN said in a statement.

Environmental officials have been monitoring compliance with the Basel Convention, which bans the transborder movement of hazardous materials, since Pemex began the process of selling the ships for scrap, the secretariat said.

"To do this, certification was obtained from Pemex and the acquiring firm that the ships were sold free of dangerous residues and were repaired and sold as ships and not as waste of any type," the secretariat said.

Both ships were sold as sailing vessels and not as scrap of any kind, the secretariat said.

The Basel Convention's secretariat has been asked to provide recommendations on the actions that should be taken by the federal government to ensure compliance with the treaty, the Environment Secretariat said.

"Any unauthorized transborder movement of hazardous materials is classified as illicit trafficking subject to the penalties provided for under domestic legislation and the Basel Convention," the secretariat said.

The Seattle-based Basel Action Network monitors compliance with the Basel Convention.

BAN said it first contacted the Mexican Environment Secretariat in October 2010 to warn officials that Pemex planned to sell the obsolete vessels to foreign salvage yards.

"At that time, the government replied, stating that they had intervened to block the sale of three Pemex tankers and imposed restrictions on Pemex's future sales to prevent the illegal export of the vessels," BAN said.

The environmental group notified the government on April 6 that Pemex planned once again to sell the ships on the grounds that the vessels would continue to be used for maritime purposes.

Pemex's move was "an apparent attempt to bypass the Basel Convention rules on disposal of hazardous waste," BAN said.

"Nevertheless, Mexican officials disregarded BAN's warning and allowed the vessels to depart for alleged re-use, only to sail directly to Pakistan and Bangladesh for scrapping last month," the environmental group said. EFE