Israel has launched a major aerial and ground offensive into the occupied West Bank city of Jenin, its biggest military operation in the Palestinian territory in years, in what it described as an “extensive counter-terrorism effort”.

At least eight Palestinians were killed and 50 injured, 10 seriously, in the attack that began at about 1am on Monday, and the death toll is likely to rise, according to the Palestinian health ministry.

On Monday afternoon, Israeli sources suggested they would need at least another 24 hours to complete the operation.

Launching at least 10 drone strikes on buildings, a brigade of Israeli troops – suggesting between 1,000 and 2,000 soldiers – backed by armoured bulldozers and snipers on rooftops entered the city and its refugee camp, encountering fire from Palestinians, after Israel informed the White House of its plans.

The streets of Jenin were deserted on Monday except for crowds of people outside the nearest hospital, watching the gun battles at the main entrance to the camp at the end of the street. Black smoke from burning tyres and teargas filled the air. Ambulances struggled to cross impromptu Israeli checkpoints.

As explosions echoed around the city, calls to support the fighters rang out from loudspeakers in mosques.

The White House said it defended Israel’s right to security and was monitoring the situation on the West Bank closely. “We have seen the reports and are monitoring the situation closely,” a White House spokesperson said. “We support Israel’s security and right to defend its people against Hamas, Palestinian Islamic Jihad and other terrorist groups.”

Britain’s prime minster, Rishi Sunak, called on the Israeli military to exercise restraint.

“While we support Israel’s right to self defence, the protection of civilians must be prioritised,” a spokesperson said. “In any military operation, we would urge the Israel Defence Forces to demonstrate restraint in its operations and for all parties to avoid further escalation in the West Bank and Gaza.”