JERUSALEM — Israel said Monday that it would mandate a two-week quarantine for anyone arriving on an international flight in a dramatic expansion of restrictions aimed at containing the coronavirus outbreak in the country.

Prime Minister Benjamin Netanyahu, in a video, said all visitors and Israeli residents arriving at Ben Gurion Airport over at least the next two weeks must proceed to 14 days of isolation. “This is a tough decision, but it is essential to maintain public health,” Netanyahu said, “and public health precedes everything.”

The isolation requirement for returning Israelis will go into effect immediately, according to the office of Interior Minister Aryeh Deri. For foreigners, the requirement is to take effect by Thursday. Foreigners will be required to prove that they have a place where they can be quarantined.

The new restrictions, among the strictest adopted by any country, come as the number of confirmed coronavirus infections in Israel reached 42. More than a dozen new cases emerged Sunday and Monday.

Among the new infections was the first case that could not be traced to international travel or exposure to a known infected person, raising the possibility of accelerating spread in the general population. More than two dozen cases have been reported in the occupied West Bank, and Israel is working with the governing Palestinian Authority to stem the outbreak there.

Officials announced a range of ramped-up measures to combat the widening outbreak, including plans to close crossings from Jordan, bar noncitizens from the emerging infection zone of Egypt and reduce movement to and from the West Bank.

The imposition of quarantine for all arriving international passengers came after several days of confused messages from the government. Critics said the decision to adopt the isolation requirement for everyone arriving from abroad was taken to avoid singling out American travelers and angering President Trump.

Israel already mandates quarantine for anyone arriving from several countries with significant outbreaks, including Italy, Japan and South Korea. Over the weekend, officials of Israel’s Health Ministry were reportedly preparing to add to that list travelers coming from New York, California and Washington state, the centers of the growing U.S. outbreak.

But local media outlets, citing sources within the Health Ministry, reported that Netanyahu objected to those recommendations out of fear they would anger Trump.

Netanyahu, who is in the middle of trying to form a governing coalition after last week’s election, spoke on the phone Sunday with Vice President Pence, the coordinator of the White House’s coronavirus response program.

Thousands of Americans and Israelis fly the air routes between the two countries. Dozens of Israelis attended the recent annual conference of the American Israel Public Affairs Committee in Washington, where at least three attendees later tested positive for the virus. Health officials said Monday that Israelis who returned from the conference after Thursday would be required to self-isolate.

Israel has been aggressive in confining the potentially exposed in their homes. As many as 80,000 Israelis are in isolation, including thousands who had to vote last week in special biohazard polling places. The military said more than 1,200 service members were in quarantine.

In the neighboring West Bank, infections have mostly been reported around Bethlehem, which has been sealed off for almost a week. That outbreak is centered on the Angel Hotel, where a Greek tourist who later tested positive for the virus had stayed. A group of American evangelical Christians from Alabama has been stranded in the hotel for almost a week.

Israel and the Palestinian Authority have reportedly been working closely on expanding coronavirus testing in the territories, along with other control measures, in an attempt to keep the West Bank’s underfunded medical system from being overwhelmed. Qatar provided $10 million to help prepare a Bethlehem hospital for the coronavirus, Mohammad Shtayyeh, the Palestinian Authority’s prime minister, said Monday.

Israel has been weighing additional restrictions on thousands of Palestinian workers, who have continued to cross into Israel from the West Bank daily. Israel’s public security minister, Gilad Erdan, on Sunday suspended visits by Palestinians to their relatives in Israeli prisons.

Fears of a widespread outbreak are growing as Israel and the West Bank prepare for some of the largest religious events of the Holy Land’s calendar. Easter, this year on April 12, typically draws large crowds of tourists to Jerusalem’s Old City, Bethlehem and other sites. Tens of thousands regularly gather for Friday prayers at the al-Aqsa Mosque during Ramadan, which begins April 23.

And Passover, which begins April 8, is normally a time when Israelis vacation abroad. But with the coronavirus disrupting travel plans and supply chains alike, retailers are predicting that an unusually large stay-home crowd will face a shortage of matzoh and other holiday items.

Ruth Eglash contributed to this report.