Mexican President Andres Manuel Lopez Obrador issued a formal apology on Monday for the mass killing of 303 Chinese in the northern city of Torreon in 1911.

"The Mexican state will not allow, ever again, racism, discrimination, and xenophobia," the president said during the ceremony in Torreon.

The event was attended by Chinese Ambassador to Mexico Zhu Qingqiao, as well as high-level Mexican officials, including the heads of the army and navy, and the foreign and interior ministers.

The mass killing, from May 13 to 15 in 1911, occurred in the midst of the Mexican Revolution, as rebels fighting under Francisco I. Madero seized control of the city of Torreon.

Over 300 Chinese were killed and their homes and businesses were burned.