Haifa Scene of bus bomb
Twelve were killed on the spot when the bomb destroyed a bus, thought to be full of university students, while three more died in hospital of their wounds.
Two 13-year-olds and two Israeli soldiers are reported to be among the dead.
The suicide bomber is believed to come from the West Bank town of Hebron, Israeli radio said.
The explosion happened on a main street at the entrance to the Carmeliya neighbourhood in the city.
Hamas and Islamic Jihad both said the attack was revenge for recent Israeli raids on Gaza.
Neither, however, claimed responsibility for the explosion.
Palestinian information minister Yasser Abed Rabbo said: 'We condemn all attacks against civilians including today's attack in Haifa.
'The attack will only serve to distract attention from the more than 150 Palestinian civilians killed by Israel over the last two months,' he said.
In Washington, President Bush's spokesman said he condemned the bombing in the strongest terms, describing it as an attack on innocents.
