ISTANBUL — The number of confirmed coronavirus cases in Turkey tripled overnight to 18 on Monday, and the government ushered in a slate of restrictions to curb the spread of the pandemic that has enveloped much of the world.

Health Minister Fahrettin Koca tweeted overnight that Turkey had 12 more cases of the novel coronavirus, including seven people who had traveled from European countries and three from the United States. At least six people have been infected by a man coming from Europe who had the country’s first diagnosis less than a week ago.

The indefinite closure of bars and nightclubs began on Monday, and was rapidly followed with another decree shuttering dozens of public spaces, from theaters to tea gardens, pools and baths, in a dramatic bid to prevent large groups from gathering and spreading the virus. Schools are shut for two weeks, and dormitories are being emptied to serve as potential quarantine centers.

Courts have postponed trial hearings except for emergencies or to decide on arrest warrants and visits to the nation’s prison population of some 282,000 people have been halted, the justice minister said. Spectators are banned from football matches and libraries, art galleries and driving schools are all closing.