MEXICO CITY — Mexico's President Andres Manuel Lopez Obrador said on Sunday he had tested positive for COVID-19 amid the country's deadliest week yet in the coronavirus pandemic, which has pushed the health system of the Mexican capital to its limits.

The 67-year-old president, who was a heavy smoker until suffering a major heart attack in 2013, said in a tweet that his symptoms were light and he was receiving treatment.

"As always, I am optimistic," said Lopez Obrador, who has resisted wearing a facemask in public since the virus reached Mexico over 10 months ago.

The president, who is back in Mexico City after a three-day visit to parts of northern and central Mexico, said he would continue working, and still planned to take part in a call with Russian President Vladimir Putin on Monday morning. — WAM