The tragedy happened in Mount Meron in northern Israel, during the festival celebrated every year on the eve of the Jewish holiday Lag BaOmer, the Xinhua news agency reported.

According to estimates by the Israeli media, about 100,000 people, most of them ultra-Orthodox Jews, participated in the festival this time.

Israeli Prime Minister Benjamin Netanyahu wrote on Twitter, "A heavy disaster on Mount Meron. We are all praying for the healing of the injured. I want to strengthen the rescue crews operating there."

Israeli President Reuven Rivlin also tweeted, "In-great concern I follow the reports from Meron and pray for the healing of the wounded. May God heal them."

It was first speculated that the tragedy was caused by the collapse of a stand, but Israeli ambulance service Magen David Adom (MDA) later said that it was caused by crowding.

The MDA added that the wounded were evacuated, some of them by helicopters, to four hospitals in northern Israel and Jerusalem.

United Hatzalah emergency medical service said that dozens of resuscitations were carried out at the site by the organisation's volunteers.