Taiwan's Central Epidemic Command Center (CECC) announced tightened Covid-19 restrictions on Wednesday after the island reported 275 new cases.
Some 267 of the infections were locally transmitted, with around 70 in the capital, Taipei, and 129 in the surrounding New Taipei City.
The Covid-19 alert level for the whole island will be raised to level 3, the second-highest grade, Taiwan's Health Minister Chen Shih-chung said. Taipei and New Taipei City were already placed under level 3 since last weekend.
Chen said Covid-19 cases have been detected in more cities across the island, which made it necessary to raise the alert level.
Changhua county on the island's central west coast reported 28 new cases Wednesday, the highest number it has seen since the pandemic began.
Under the new restrictions, no more than five people may gather indoors at any one time, and no more than 10 people may gather outdoors. Some non-essential facilities will also be closed.
The island's current Covid-19 outbreak is relatively small compared to those in other parts of the world, but is an unfamiliar situation for Taiwan, which has until now managed to avoid a serious spike in cases.
Taiwan is expected to receive 400,000 additional doses of AstraZeneca Covid-19 vaccines from the Netherlands on Wednesday, according to the official Central News Agency.
The island has one of the lowest vaccination rates in the world, with fewer than 1% of its 23 million-strong population inoculated, according to data compiled by CNN.