Carrie Lam, chief executive of China's Hong Kong Special Administrative Region (SAR), said that a strike by medical employees has impacted hospital services and patients.

"Because some medical staffs have not returned to work, hospital services in Hong Kong and many patients in critical condition are affected," Lam said at a press conference on Tuesday.

Thousands of doctors and nurses went on strike on Monday in Hong Kong, demanding a total shutdown of the border with the Chinese mainland in order to prevent the spread of the coronavirus outbreak. Their move has drawn criticism in Hong Kong for leaving medical institutions understaffed at such critical moments.

Hong Kong authorities have announced they are closing four more border crossings starting Tuesday. On January 31, six checkpoints were closed.

Lam said the SAR government puts the needs of medical personnel first, and prioritizes the resources and materials they need. She said she "appreciates the medical staff who are still carrying out their duties."

The Hong Kong SAR chief said the closure of the border crossings has no effect on freight transportation, and noted that there are currently no shortages of food or essential supplies in Hong Kong amid panic buying.