GAZA CITY, Gaza Strip ? Palestinian security forces began a series of raids in the Gaza Strip, seizing weapons, shutting down two smugglers’ tunnels between Egypt and the Gaza Strip, and arresting at least 12 smugglers, a Palestinian security official said Saturday.

It was not clear whether the raids marked the start of a clampdown on militants demanded by Israel and the United States. Such a campaign could help defuse growing tension, triggered by a Hamas bombing of a Jerusalem bus this week and the killing of a Hamas leader in an Israeli missile strike.

The violence threatens to sink a U.S.-backed “road map” peace plan that envisions Palestinian statehood by 2005.

Israeli Foreign Ministry official Gideon Meir said Saturday’s action was not enough, and Israel expects Palestinian security chief Mohammed Dahlan to arrest those involved in violence against Israel.

“We expect Dahlan to take his 20,000 troops and to start making arrests of the terrorists,” he said. “We don’t need any more words.”

In a political development, the central committee of Yasser Arafat’s Fatah movement nominated longtime Arafat aide Lt. Gen. Nasser Yousef for the post of interior minister, said Hany Al-Hassam, one of 12 committee members.

The interior minister has broad responsibility for security matters, and Palestinian Prime Minister Mahmoud Abbas, who currently holds the role, asked Dahlan to assume some of those duties. It was unclear how the nomination, which still must be approved by the legislative council, would affect Dahlan’s position.

Palestinian legislator Saeb Erekat said the closing of the tunnels reflects the Palestinian Authority’s determination to enforce the law.

“The obstacle to this (crackdown) now is the Israeli policy of incursions, assassinations, building walls and noncompliance with the road map,” he said.