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Palestinian militants holding an Israeli soldier angrily said Tuesday they would not release any information about the serviceman's condition after Israel ignored a deadline to begin releasing Palestinian prisoners. But as diplomatic efforts continued, the militants said they would not kill the soldier.

The militants implied Monday they would kill Cpl. Gilad Shalit if their demands weren't met. Israel rejected the demands and insisted Tuesday it would not negotiate with the militants.

After a 6 a.m. deadline passed, a spokesman for the shadowy Army of Islam said the groups holding Shalit "have decided to freeze all contacts and close the files of this soldier."

"We will not give any information that will give the occupation good news or reassurance," said the spokesman, Abu Muthana. But, he added, "We will not kill the soldier, if he is still alive."

The previously unknown Army of Islam was among three groups that took part in the June 25 cross-border raid that killed two Israeli soldiers and abducted Shalit, 19. Two other groups, the military wing of the ruling Hamas party and the Hamas-linked Popular Resistance Committees, also claimed responsibility.

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CountryWatch: Israel

Since the abduction, the militants have called on Israel to release hundreds of prisoners in exchange for information about Shalit. The abductors have given no concrete information about the soldier's condition, though Israeli officials believe he is alive.

Israeli Prime Minister Ehud Olmert has rejected any negotiations with the militants, and last week launched a ground invasion in the Gaza Strip aimed at pressuring the Hamas-led Palestinian government to secure the soldier's release.

Cabinet minister Roni Bar-On, who is close to Olmert, said there was no change in the Israeli position after Tuesday's deadline passed. "Israel will not give in to terrorists and will not give in to extortion," he told Israel Radio.

Despite the tough public line, Israeli officials have privately said they would consider other options to get the soldier back. Israel has released prisoners before in lopsided exchanges for captured citizens or the dead bodies of soldiers killed in battle.

Egypt has been leading international mediation efforts to solve the crisis, including talking to Syria, whose president, Bashar Assad, is believed to hold influence over Hamas' Syria-based political head, Khaled Mashaal.

Abu Muthana said the Army of Islam has been approached by Muslim leaders asking it to give more time to find a peaceful resolution. He said the group was considering the request.

Hamas sent out mixed messages late Monday. In Gaza, government spokesman Ghazi Hamad expressed hope for a diplomatic solution.

But Osama Hamdan, one of the most senior members of the exiled Hamas leadership, ruled out a compromise and threatened to abduct more Israelis.

"If this operation does not lead to the release of prisoners now, let's postpone talk ... and we will continue resistance. Other (Israelis) might be taken prisoner," Hamdan, Hamas' representative in Lebanon, told Al Manar television.

In the West Bank city of Ramallah early Tuesday, after surrounding a Palestinian police building, Israeli forces arrested three militants said to be involved in the abduction and killing of an 18-year-old Israeli settler last week. The military said a fourth was arrested earlier.

The kidnapping of the teen, Eliahu Asheri, added tension to the situation surrounding the capture of the soldier. Asheri's body was found Thursday near Ramallah.

In the hours before the deadline expired, Israel kept up its pressure on Hamas with airstrikes.

Early Tuesday, Israeli aircraft hit the student council building at the Islamic University in Gaza City, witnesses said, badly damaging it. No one was hurt. The university is a Hamas stronghold. The military said it hit a "compound used by terror groups for instructing and directing terrorists."

The military said it also hit another Hamas facility in northern Gaza.

Also, Palestinian residents said several Israeli tanks and a bulldozer entered the northern Gaza town of Beit Hanoun after midnight. The military said they were still outside. Israel has been building up troops across from northern Gaza, preparing for an invasion.

A Hamas militant was killed and four wounded in an Israeli airstrike in Beit Hanoun in northern Gaza just after midnight, Palestinians said. Israel said its air force targeted Palestinians planting a bomb near soldiers' positions.

The White House and European Union have urged the militants to release Shalit, while also calling on Israel to show restraint.

"It is the responsibility of Hamas to return the Israeli soldier. That's how all this got started. We have also been encouraging Israel from the very beginning to practice restraint and continue to do so," White House press secretary Tony Snow said.

Many Palestinians say they do not wish Shalit to be harmed, but they back the demand to free some of the 9,000 Palestinian prisoners held by Israel.

"I think they should release the women and children and [the militants should] release the soldier. But without anything in return, they'll kill him," said Saked Abu Kosh, a 30-year-old pharmacist in the southern town of Rafah.