MEXICO CITY (Reuters) - The Russian government has launched a sophisticated campaign to influence Mexico’s 2018 presidential election and stir up division, a senior White House official said in a video clip published by Mexican newspaper Reforma.

FILE PHOTO: National security adviser Lt. Gen. H.R. McMaster speaks at the FDD National Security Summit in Washington, U.S., October 19, 2017. REUTERS/Yuri Gripas

U.S. National Security Adviser H.R. McMaster said in a speech last month to the Washington-based Jamestown Foundation that there was already evidence of Russian meddling in Mexican elections set for July.

“We’ve seen that this is really a sophisticated effort to polarize democratic societies and pit communities within those societies against each other,” said McMaster in a previously unreported video clip from Dec. 15 that was posted on Twitter by a reporter with Mexican daily newspaper Reforma on Saturday.

“You’ve seen, actually, initial signs of it in the Mexican presidential campaign already,” said McMaster, a former Army general. He did not elaborate in the clip on how Russia was seeking to influence the election.

Reforma published a story on Saturday on the comments, which have since been shared many times on social media.

President Donald Trump’s senior national security aide added in the clip that the U.S. government was concerned by Russia’s use of advanced cyber tools to push propaganda and disinformation.

A request for comment sent to McMaster’s office at the White House and a request for comment from the Russian government in Moscow were not immediately returned on Sunday.

The Kremlin has repeatedly denied accusations by U.S. intelligence officials and others of interfering in foreign elections.

In July, Mexico will elect a new president to succeed Enrique Pena Nieto, who is barred by law from seeking a second six-year term. Congressional seats plus some governors’ races will also be up for grabs.

According to opinion polls, the frontrunner in the presidential contest is the leftist former mayor of Mexico City, Andres Manuel Lopez Obrador, who is running on an anti-corruption platform.

Lopez Obrador, a two-time runner-up for the presidency and a divisive figure in Mexican politics for over a decade, is seen by some analysts as the Kremlin’s favorite, given the positive coverage he has received from government-funded media outlets like Sputnik and Russia Today.

Both China and Russia are taking an increasing interest in Latin America as the United States, under Trump, has adopted a more protectionist stance and the future of the North America Free Trade Agreement looks uncertain.

Lopez Obrador has been a fierce critic of Pena Nieto’s sweeping energy overhaul, which was favored by U.S. officials and oil companies. He has said he would seek friendly relations with the U.S. government but would demand respect.

In 2016, Russia Today’s Spanish-language YouTube channel began running a weekly video blog entitled “The Battle for Mexico,” hosted by a prominent supporter of Lopez Obrador, according to David Salvo at the German Marshall Fund of the United States, who has written about Russian attempts to influence politics in Latin America.

Pena Nieto’s office and the foreign ministry did not immediately respond to a request for comment on McMaster’s statement.

Some Mexican political commentators said that there was little reason yet to fear Russian involvement in the election.

“The point is that Washington hasn’t provided any solid proof for this,” said Marco Cancino, head of Mexico City-based consultancy Inteligencia Publica.

“So far, it’s just speculation.”