Mexico’s government has said it wants to remain neutral in the conflict, and some supporters of Ukraine have criticised the country’s leftist president Andres Manuel Lopez Obrador for taking issue with European arms shipments to Kyiv.

Still, Mexico has voted alongside the US and other Western powers on a number of major UN resolutions.

The speech was due to take place around midday Thursday, the sources said.

Zelensky’s address to the lower house of Congress came at the invitation of a congressional friendship group between Mexico and Ukraine, according to the sources. There are other similar groups in the Mexican Congress, including one for Russia.

The Ukrainian embassy in Mexico did not immediately reply to a request for comment.

The German president and the US ambassador to Mexico have been among diplomatic allies that have sought to persuade the Mexican government to side with Ukraine against Russia.

Attempts to sway public opinion in Mexico over the war in Ukraine have led to some notable spats in Congress.

Last year, the Russian ambassador to Mexico told Mexican lawmakers that Mexico would never take orders from “Uncle Sam”, prompting the US ambassador to urge Mexico to support Ukraine.

Lopez Obrador last year proposed a plan to halt the fighting in Ukraine, although Ukrainian officials opposed it, arguing it would be advantageous to Russia.

Mexican foreign minister Marcelo Ebrard met separately with his Russian and Ukrainian counterparts to discuss the peace plan at the UN General Assembly in September. Nothing has come of the plan so far.

Russian foreign minister Sergei Lavrov is currently on a Latin American tour, visiting Brazil, Venezuela, Nicaragua and Cuba.