By Dan Williams and Jeffrey Heller

JERUSALEM (Reuters) – Prime Minister Benjamin Netanyahu said on Wednesday lockdown orders would be issued unless people stepped up compliance with guidelines urging them to stay at home to help halt the spread of the coronavirus in Israel.

In a controversial new measure for containing infections, the Health Ministry said it alerted people who had been exposed to coronavirus carriers, based on information it gleaned through “technological means” – an apparent reference to cyber-surveillance on loan from the Shin Bet counter-terrorism agency.

“Yesterday we gave clear instructions … asking people to stay at home as much as they can and to go outside only when it’s vital, for food supplies and other such needs we specified,” Netanyahu said in an interview with Channel 12 TV.

But, Netanyahu said, some members of Israel’s ultra-Orthodox Jewish community and “part of the minorities” – a reference to its 21-percent Arab minority – have not taken in the message.

“If the message is not understood, then I will not hesitate to impose an order.”

He gave no details on the extent of any lockdown and said he would address the issue further in public remarks on Thursday.

A lockdown, enforced by police under government order, would put further strain on the Israeli economy, The government has already announced a 15 billion shekel ($4 billion) aid package to help businesses damaged by the crisis and boost health services.

Confirmed coronavirus cases in Israel numbered 433. An earlier tally on Wednesday marked a 40% jump from Tuesday.

In the interview, Netanyahu cited instances in which large weddings were held by the ultra-Orthodox community while some religious schools remained open despite a national closure of educational institutions.

The Health Ministry has limited gatherings to no more than 10 people. Many businesses have reduced staff. Restaurants have shifted to delivery-only operations and public transport has been cut back. Supermarkets remain open. On Wednesday, Israel imposed a blanket ban on entry by foreigners.

The Health Ministry said it sent text messages to around 400 people instructing them to self-isolate because they had been within infection distance of a coronavirus carrier.

The Netanyahu government fast-tracked approval for access to Israelis’ communications data.

Israel’s Supreme Court was due on Thursday to hear challenges to the Shin Bet’s involvement by civil liberties activists who fear it will open the door to domestic spying.

Netanyahu said testing for coronavirus infection would be stepped up, with 3,000 tests administered daily, which will rise to 10,000 a day within two weeks.

No fatalities from the coronavirus have been reported in Israel or in the Palestinian territories to date.

But Moshe Bar Siman-Tov, the Israeli Health Ministry’s director-general, told Army Radio that he expected there would be “many hundreds of new patients each day, and possibly more”.

In the Israeli-occupied West Bank, the Palestinian Authority announced tighter restrictions on the movements of Palestinians, saying no one could enter or leave the biblical town of Bethlehem and its residents must remain indoors.

Palestinian health officials have confirmed 44 cases of coronavirus infection. None has been detected in the Gaza Strip, where Israel and Egypt enforce tight border restrictions.

(Additional reporting by Maayan Lubell, Ali Sawafta and Nidal al-Mughrabi; Editing by Jeffrey Heller, Mark Heinrich and Grant McCool)