Israeli attacks in the Gaza Strip on Wednesday killed 10 Palestinians, including a 12-year-old boy, Palestinians said, the bloodiest fighting in the area since the Hamas militant group violently seized control two weeks ago.

The sudden burst of violence came as the "Quartet" of Mideast peace mediators -- the U.S., EU, U.N. and Russia -- was expected to name outgoing British Prime MinisterTony Blair as its new envoy. A formal announcement was expected Wednesday, but Irish Prime Minister Bertie Ahern said Blair had already accepted the post.

"I spoke to him about this on Friday night. I can tell you that's exactly what he's going to do," Ahern told Irish state broadcasters RTE. Ahern said Blair told him the mission would be "tricky, but he believes if there's persistent engagement -- it's like in Northern Ireland, where you just have to stay at it."

In the new position, Blair would take on a task that has bedeviled many before him. The last Quartet envoy, former World Bank chief James Wolfensohn, stepped down in frustration after less than a year on the job following Israel's withdrawal from Gaza in 2005.

Blair's role is complicated by Hamas' takeover of Gaza, the weakness of Palestinian and Israeli leaders, and animosity deepened on both sides by six years of conflict. Still, the outgoing British prime minister brings new credibility to international efforts to forge peace in the region. Officials in Israel and Palestinian President Mahmoud Abbas' Fatah movement already have reacted positively to the prospect of working with him.

Israeli Prime Minister Ehud Olmert called Blair on Tuesday night to wish him well as he left office, the Israeli leader's office said. Olmert told Blair "that he is a true friend of the state of Israel and added that if he accepts the position of the Quartet envoy to the region, Israel would cooperate with him to the fullest," the statement said.

Hamas, however, was not enthusiastic. The Islamic militant group, which recently routed Fatah forces in Gaza, said Blair was too close to the U.S. and would not be an impartial mediator.

"We expect Blair will not be a good man in this position," said Hamas spokesman Ghazi Hamad. "In the time he was prime minister of Britain, he was not honest and was not helpful in solving the conflict."

In Wednesday's violence, two detachments of Israeli tanks and troops pushed into northern and southern Gaza, exchanging fire with Palestinian gunmen.

Israeli fire struck a Gaza City house, killing four people, including a 12-year-old boy, medics said. Witnesses said militants were seen in the area. Five militants were killed in fighting with the Israelis in another outlying part of the city, Palestinians said.

In southern Gaza, an Islamic Jihad militant was killed in a clash with troops in the town of Khan Younis. Hospital officials said a total of 40 people were wounded by Israeli shells in Gaza City.

Two more Palestinians died in other violence. In Khan Younis, a Hamas militant was killed while mishandling explosives, and a senior Islamic Jihad member was killed in what Palestinians said was an airstrike. Israel, which usually acknowledges airstrikes, denied involvement.

The army said two soldiers were wounded when their tank was hit by a shoulder-launched rocket.

Palestinians fired a rocket into Israel, but it struck open ground near the Gaza border, causing no casualties, the army said. Several mortar shells were also fired at Israel but fell short, landing on the Gaza side, the military said.

The death toll was the highest in a single day since Hamas seized control of Gaza two weeks ago after routing the Fatah forces. The takeover has left the Palestinians with a Hamas government in Gaza and a Fatah government in the West Bank.

In a fresh attempt to consolidate his rule over the West Bank, Abbas ordered all armed groups, including those linked to his own Fatah movement, to disarm immediately, officials said Wednesday.

A decree issued late Tuesday formally outlawed armed groups that are not part of the official government security forces, but made no reference to how the ruling would be enforced.

"All kinds of militias and military groups are banned, no matter to whom they belong," an official in Abbas' office on Wednesday quoted the decree as saying. "The government must end the phenomenon of military groups and is required to implement the law that bans carrying any kinds of weapon or explosives."

While Fatah is believed to be much stronger than Hamas in the West Bank, there are fears the Islamic group will seek to flex its muscles there too. Still, it was unclear whether Abbas would be able to carry out the crackdown.

In addition to official security forces, thousands of gunmen from Hamas, the pro-Fatah al-Aqsa Martyrs' Brigades and smaller militant groups live in the West Bank, and past attempts disarm them have failed.

Zakariye Zubeydi, a leader of the Al Aqsa Martyrs' Brigades in the West Bank, said he supported Abbas' efforts to disarm Hamas and other armed groups -- but said his group would not give up its weapons. "We shall continue to defend our people where they are with our weapons," he said.

Sami Abu Zuhri, a Hamas spokesman in Gaza, accused Abbas of caving in to Israeli pressure. "All Palestinians hold fast to right of resistance," he said. "These plans will not succeed at hurting this right."

If Abbas is successful, it would mark a significant step in his efforts to restart peace talks with Israel. The Quartet's "road map" peace plan calls on the Palestinians to disarm militants, while requiring Israel to halt settlement activity in the West Bank. Neither side has met its obligations.

Israel and the international community has rallied behind Abbas in his standoff with Hamas. Israel has promised a series of goodwill gestures, including a release of Palestinian prisoners and transfer of withheld tax funds, and expressed willingness to work toward a resumption of peace talks.

Officials say Blair's main task will be to strengthen Palestinian institutions to help lay the groundwork for a future independent state.

Complete coverage is available in FOXNews.com's Mideast Center.