MEXICO CITY - A LEADER of Mexico's powerful Gulf drug cartel, Ezequiel Cardenas Guillen, also known as 'Tony Tormenta,' was killed on Friday in a shootout with soldiers in north-eastern Mexico, officials said.

'Ezequiel Cardenas Guillen, leader of the Gulf criminal organisation, was brought down,' public security spokesman Alejandro Poire told journalists.

Three outlaws and two members of the security forces were also killed during the firefight in the border city of Matamoros, across from the US city of Brownsville, Poire said. A local newspaper, El Expreso, said one of its journalists also died in the shootout in Tamaulipas state, which has seen an escalation of violence in recent months blamed on turf wars between the Gulf cartel and its former allies the Zetas.

Guillen had been on a list of Mexico's most wanted drug gang leaders, with a reward of up to US$2.5 million (S$3.2 million) on his head.

The US Drug Enforcement Administration (DEA) had offered up to US$5 million for information leading to his arrest and capture. He was considered a key smuggler of marijuana and cocaine into the United States.

The 48-year-old took over a leadership role in the Gulf cartel after the 2003 capture of his brother, Osiel Cardenas Guillen, a former leader of the gang who was later extradited to the United States.

Gulf cartel leader killed