MEXICO CITY — Mexican security forces killed a leader of the violent Knights Templar drug cartel on Monday, officials said.

The cartel has created a major security problem for President Enrique Pena Nieto in the western state of Michoacan, where it has been fighting vigilante groups.

Enrique Plancarte was killed by Mexican marines in an operation in Michoacan, security officials said.

"The identity of Enrique Plancarte, believed killed in a confrontation with marines, is being confirmed," Mexico's security ministry said via Twitter, adding that it would provide more information on Tuesday.

Earlier this year, security forces captured another senior Knights Templar member, Dionisio Loya Plancarte, known as "El Tio" ("The Uncle").

Since taking office in December 2012, Pena Nieto has sought to shift public attention to his efforts to reform the economy and away from grisly violence that has killed more than 80,000 people since his predecessor, Felipe Calderon, launched a military offensive against drug cartels seven years ago.

U.S. agencies last month helped Mexico capture the world's most-wanted drug kingpin, Joaquin "Shorty" Guzman, marking a major victory for Pena Nieto's government.