Mexican President Andrés Manuel López Obrador has tested positive for COVID-19, his office confirmed Monday, adding that his symptoms are mild and he is now being treated by doctors.

Obrador, who has been criticized for his administration's response to the pandemic, published a post on Twitter Sunday informing the public of his condition.

"I regret to inform you that I am infected with COVID-19. The symptoms are mild but I am already under medical treatment. As always, I am optimistic. We will all move forward," Obrador said in his post.

Mexico's director of epidemiology, José Luis Alomía Zegarra, also said that the president and his family have now been quarantined at their home.

While Obrador is under quarantine, Interior Secretary Olga Sánchez will reportedly be taking over some of his duties, including his daily news conferences. Obrador usually speaks for two hours during his daily news conferences on weekdays.

Similar to some global leaders, the 67-year-old politician has rarely been seen in public wearing a mask.

He has also resisted locking down the country, saying that would only serve to devastate the economy and affect many Mexicans who live day-to-day. Mexico had registered a total of around 150,000 coronavirus-related deaths and more than 1.7 million positive cases.

In November, the World Health Organization urged Obrador's government to take the coronavirus pandemic seriously. The head of the agency, Tedros Adhanom Ghebreyesus, previously said that Mexico was "in bad shape" and officials need to set an example for its citizens.