At least 44 have people have been killed in a crowd crush and stampede at a religious festival attended by tens of thousands of people in northern Israel early on Friday morning.

More than 150 others were injured in the incident that took place as ultra-Orthodox Jews were celebrating the holiday festival of Lag Ba'Omer with singing, dancing and bonfires at the foot of Mount Meron in Galilee to honor Rabbi Shimon Bar Yochai, who is buried there.

During the night, emergency services transported casualties by ambulance and helicopter to hospitals in northern and central Israel with added support from the police and the army.

All of the injured have now been evacuated, according to the police.

The stampede was caused after some revelers slipped on steps, causing a 'human avalanche' that crushed many, local media reported.

While the exact cause of the stampede has not been established by authorities, a spokesman for emergency service United Hatzalah told EFE it could have been due to overcrowding.