* Israeli air strikes kill eight Palestinians - health officials
* Comes after Palestinian mortar bomb kills Israeli boy
* Egypt-mediated peace talks broke down on Tuesday (Adds Palestinian president's comments)
By Nidal al-Mughrabi and Maayan Lubell
GAZA/JERUSALEM, Aug 23 (Reuters) - Palestinian President Mahmoud Abbas called for an urgent resumption of peace talks on Saturday as violence continued unabated in the Gaza Strip with Israel carrying out air strikes and militants firing rockets.
Gaza health officials said five people, including two children, were killed in an Israeli strike on a house in central Gaza. Three more Palestinians were killed in other strikes.
The Israeli military said it bombed about 20 targets across the Hamas-dominated strip, including rocket launchers and weapon caches. It said Gaza militants had fired more than 20 rockets at Israel and no Israeli casualties were reported.
Indirect talks between the sides, brokered by Egypt, collapsed on Tuesday after rockets were fired from Gaza during a ceasefire and Israel responded with air strikes.
The Israeli military said Palestinian gunmen had fired almost 500 rockets at Israel since the talks broke down and Gaza health officials said 65 Palestinians had been killed in Israeli air strikes since then.
Abbas called on Saturday for both parties to return to the negotiations which aim to end the six-week-old conflict and seal a deal that would open the way for reconstruction aid to flow into the Gaza territory of 1.8 million people where thousands of homes have been destroyed.
"My main goal is for the truce talks to resume in Egypt as soon as possible to avoid more casualties," he told a news conference after meeting Egyptian President Abdel Fattah al-Sisi.
Palestinian health officials say 2,079 people, most of them civilians, have been killed in the small, densely populated coastal enclave since July 8, when Israel launched an offensive with the declared aim of ending rocket fire into its territory.
Saturday's violence came a day after a four-year-old Israeli boy was killed by a mortar attack from Gaza, leading Israeli Prime Minister Benjamin Netanyahu to threaten to escalate the fight against Hamas, vowing the group would "pay a heavy price".
The boy was the first Israeli child to have died in the conflict, bringing to four the number of civilians killed in Israel. Sixty-four Israeli soldiers have also been killed.
The Israeli military had said on Friday the mortar was fired from a school serving as a U.N. shelter, but later retracted that statement, saying the shelter was run by Hamas.
On Friday Hamas-led gunmen in Gaza executed 18 Palestinians accused of collaborating with Israel. The Independent Commission for Human Rights, a Palestinian rights group, said there were two women among those killed.
Masked militants dressed in black executed seven suspected collaborators, shooting the hooded and bound victims in a busy square outside a mosque. The deaths followed the killing of 11 alleged informers at an abandoned police station.
The crackdown on suspected collaborators followed the killing of three of Hamas's most senior military commanders in an Israeli air strike on Thursday, an attack that required precise on-the-ground intelligence on their whereabouts.
On Friday, Israel's military spokesman Brig. Gen. Motti Almoz warned Palestinians near weapons stockpiles in Gaza to leave their homes. "We are intensifying our attacks," he said, adding that Israel was "preparing for possible ground action".
Israel pulled ground forces out of Gaza more than two weeks ago after saying it had destroyed a network of Hamas tunnels used for cross-border ambushes. But Netanyahu last week granted provisional approval for the call-up of 10,000 army reservists, signalling the possibility of heightened military action.
Israeli attacks have devastated many areas in the impoverished Gaza Strip. The United Nations says about 400,000 Gazans have been displaced and more than 400 children killed in the longest and deadliest violence between Israel and the Palestinians since the second Intifada, or Palestinian uprising, a decade ago. (Additional reporting by Yasmine Saleh in Cairo; Writing by Maayan Lubell; Editing by Pravin Char)