Refusing to take a neutral stand, the Bush administration said Thursday there was no equivalence between an Israeli attack in Gaza (search) that killed members of terror groups and bystanders, and a Palestinian homicide bombing on a bus in Jerusalem (search).

"We don't draw equivalence between different actions," State Department spokesman Richard Boucher said from a podium where past administrations have carefully and evenhandedly deplored violence on both sides with equal emphasis.

"I am not here to draw comparisons between different actions," Boucher said. He also stressed that Israel had a right to self-defense and that Palestinian violence was hurting peacemaking prospects.

Eight Palestinians were killed Wednesday by Israeli troops in Gaza. Four were from the Islamic Jihad (search) group and a fifth from Hamas (search). The State Department identifies the two groups as terrorist organizations. Another three people killed were bystanders.

Militant Palestinians vowed vengeance. On Thursday, a Palestinian policeman bombed a bus near Israeli Prime Minister Ariel Sharon's residence in Jerusalem, killing 10 Israelis and wounding 50 other people.

The attack disrupted efforts by two senior State Department officials, David Satterfield and John Wolf, to set up high-level talks between Israeli and Palestinian officials.

Powell, meeting with Turkish Foreign Minister Abdullah Gul at the State Department, called the attack horrendous and said both men condemned it.

"Once again, terrorists have killed innocent people, and at the same time they have struck a blow once more against the aspirations of the Palestinian people to have a homeland of their own," Powell said.

"This kind of action has got to stop," he said, appealing publicly to Palestinian Prime Minister Ahmed Qureia "to do everything in his power" to go after the terrorists.

Three weeks ago, Powell placed the blame for the impasse in Mideast peacemaking on Palestinian leaders, saying they had failed to counter terror against Israel.

On Thursday, he suggested Qureia was still not taking action against terror groups. "It is time to end the terror, and the Palestinian leadership has to realize this and face it," he said.

Powell also lashed out at Syria, saying it could not be serious about wanting a peace accord with Israel as it continues to trans-ship weapons that are going to terrorists "of the kind who killed innocnt people this morning in Jerusalem."

Later, Boucher dismissed Syrian claims that it has closed down all but information activities of anti-Israel militant groups in Damascus.

He said any office that supports terrorist group should be closed. And Boucher said Syria had taken only "limited steps" to keep fighters from crossing into Iraq for attacks on Western peacekeepers.