Hong Kong will step up countermeasures to tackle the coronavirus outbreak as a surge in imported cases could crash the local medical system, leader Carrie Lam warned Saturday.

Nearly 90 percent of the new confirmed cases reported since early March have been imported ones, Lam said in a news briefing.

"The aggravating situation of the outbreak due to rising imported cases could be long-lasting," Lam said. "The medical system could be crippled should there be a surge in cases."

(File photo shows Carrie Lam (L))

Surveillance on incoming visitors will be enhanced under the 14-day compulsory quarantine arrangement in place since Thursday, she said, adding that those found in breach of the quarantine order will be prosecuted without prior warning.

The maximum penalty for the offense is six months' imprisonment and a fine of HK$25,000 (about $3,200).

She also said that civil servants, who had begun to return to their offices since March 2, would resume working from home on Monday while non-essential public services will be suspended.

Schools will remain closed while high school examinations are to be postponed for another month to the end of April, Lam said.

Seventeen new confirmed cases have been reported, taking the territory's total to 273. Most of the new cases have traveled overseas before falling ill, according to health officials.

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