LAGOS, Nigeria (AP) — Nigeria’s anti-drug agency said it has busted a transnational organized drug syndicate involving Nigerians and Mexicans in the southwestern region of the country.

The National Drug Law Enforcement Agency said late Wednesday that its special operations unit shut down “an industrial-scale clandestine laboratory” in a remote forest in the Ijebu area of Ogun state, which shares a border with Lagos, the country’s economic capital. The agency added that it is the biggest drug bust ever in the country.

The agency said in a statement that it arrested seven members of the “cartel,” which included four Nigerians and three Mexicans, during the operation, and three more in follow-up arrests.

“This network did not just traffic drugs; they were actively manufacturing industrial-scale quantities of highly lethal illicit substances right on our soil, threatening the national security and public health of Nigeria,” Brig Gen Mohamed Buba Marwa, the agency’s head, said.

According to the statement, the operation resulted in the seizure of 2.4 tons of chemical materials, including methamphetamine, worth 480 billion naira ($363 million) and two vehicles.

In recent years, West and Central Africa have emerged as a hot spot for global trafficking and manufacturing of illicit drugs due to porous borders and corruption, according to the United Nations Office on Drugs and Crime.