Updated

Israeli authorities on Tuesday said they have arrested 19 Palestinian militants for planning to set off a huge car bomb in Tel Aviv over the Jewish holiday of Passover.

The suspects are all were Hamas members from the West Bank town of Qalqiliya, the Shin Bet security agency said in a statement.

The agency said the arrests took place in late March, but details were only cleared for publication on Tuesday, the day after the weeklong holiday ended.

Hamas officials in Qalqiliya denied the account and said they were not involved in any plot.

Shin Bet said a Palestinian man who apparently intended to blow himself up drove a car packed with 220 pounds of explosives into the Tel Aviv area, then, for reasons not yet clear, returned to Qalqiliya where the car later exploded through a technical malfunction. No one was hurt.

The would-be bomber was able to enter Israel unhindered because he has an Israeli Arab stepmother and holds an Israeli identity card, Shin Bet said. It said the car had Israeli license plates.

The Israeli daily Haaretz said the plot was ordered by Hamas renegades in the Gaza Strip who are displeased with the movement's November cease-fire with Israel and its acceptance of the more moderate Fatah movement into a coalition government.

"Hamas, the senior member in the new Palestinian government, continues to pursue a terror-laden agenda and refuses to abandon the terror option. The Palestinian government is one to be shunned until it forsakes terror and recognizes Israel," said David Baker, an official in the Israeli prime minister's office.

Palestinian police officials in the town said the 19 suspects weren't connected to any bombing. They said the militants were rounded up at a Hamas ceremony marking the third anniversary of the Israeli assassination of the group's founder, Sheik Ahmed Yassin.

Police said the car held less than 2 pounds of explosives and that it was unlikely Hamas was connected because the bomb was so small. However, they said it remained unclear why the car was carrying explosives.