The World Health Organization on Wednesday declared the novel coronavirus a pandemic after weeks of avoiding the use of the designation while the outbreak spread across the globe.

"We have rung the alarm bell loud and clear," Tedros Adhanom Ghebreyesus, WHO director general, said at a news conference.

Tedros said that in the past two weeks, the number of cases outside of China have increased thirteenfold, and the number of affected countries has tripled.

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Health officials have recorded more than 120,000 cases of the virus across the world and more than 4,000 deaths.

"In the days and weeks ahead, we expect to see the number of COVID-19 cases, the number of deaths and the number of affected countries to climb even higher," Tedros said.

He added, "We have never seen a pandemic that can be controlled at the same time."

"Even those countries with community transmission or large clusters can turn the tide on this coronavirus," Tedros said.

As cases and deaths in China have dramatically fallen, the situation has worsened in other countries, like Italy and Iran.

WHO has held off on declaring the virus a pandemic , citing concerns about the potential reaction to the classification.