U.S. Ambassador Ken Salazar has rejected accusations by Mexico’s president that the U.S. shares some responsibility for cartel violence in Sinaloa state.

The uptick in violence comes after the surprise arrest on U.S. soil of Sinaloa Cartel co-founder Ismael "El Mayo" Zambada in July.

Some 53 people have been killed and 51 others are missing in Mexico's western Sinaloa state since rival factions of the Sinaloa Cartel began clashing on Sept 9, local authorities said on Friday, with gruesome violence showing no signs of abating.

At least 30 people have been killed in the past two weeks in Mexico’s northern state of Sinaloa as two factions of the powerful Sinaloa cartel continue to clash.

The U.S. ambassador to Mexico on Saturday rejected President Andres Manuel Lopez Obrador's claims that the U.S. was "co-responsible" for violence in the western state of Sinaloa, where more than 50 people have died in an intra-cartel war this month.

U.S. intelligence analysts suggest the conflict could last for years. The Drug Enforcement Administration reports the Sinaloa and Jalisco cartels have a presence in all 50 U.S. states, controlling global networks that dominate the fentanyl and methamphetamine trade.

Two warring factions of the Sinaloa cartel have clashed in the state capital of Culiacan in what appears to be a fight for power since two of its leaders were arrested in the United States in late July.