JERUSALEM (AP) _ Palestinian police caught two Hamas activists with 130 pounds of explosives near the border between Israel and the Gaza Strip, a security official said Friday.

The men apparently had planned to give the explosives to other members of the Islamic militant group Hamas who were to sneak across the border into Israel to carry out a bombing attack, said the official who spoke on condition of anonymity.

Meanwhile, Israel today sealed off its borders with the West Bank and Gaza Strip indefinitely amid warnings that Hamas plans bombing attacks. The restrictions bar the more than 2.5 million Palestinians in the West Bank and Gaza from entering Israel.

Israeli Defense Minister Yitzhak Mordechai imposed the closure after consulting with top army generals. Mordechai reportedly told the Israeli Cabinet on Thursday that Hamas planned an ``unprecedented, horrific'' attack in Israel.

Hamas has threatened retaliation for the Sept. 11 killings of two Hamas fugitives by Israeli soldiers. Since 1994, Hamas has carried out more than a dozen suicide bombings.

The two Hamas activists, along with the driver of their getaway car, were arrested Sept. 24 near the Nahal Oz crossing between Gaza and Israel. The case was not made public because Palestinian police hoped to catch accomplices still at large, the official said.

The security official denied an Israel radio report that Palestinian police seized videotapes in a hideout used by the two men. Suicide bombers routinely leave behind videotapes in which they explain their actions and say good-bye to their families.

In recent days, Hamas suffered a series of setbacks. On Monday, Palestinian police raided a Hamas bomb factory in the West Bank town of Hebron and seized nearly a ton of explosives. A week ago, a Hamas activist was killed when a car rigged with explosives blew up.

The leader of the group, Sheik Ahmed Yassin, acknowledged Thursday that Hamas was facing difficulties in carrying out attacks because of searches and arrests by Israeli and Palestinian troops.

However, Yassin said a Hamas ``response will come at the appropriate time, even if it is delayed.''