The European Parliament has backed the findings of a UN-backed report into last year's Gaza war, which heavily criticised Israel and accused both Tel Aviv and Hamas of war crimes.
The assembly is the second institution after the United Nations to stand in favour of the report, with just over 50 per cent of politicians passing the resolution.
It urged its 27-member states to monitor Israeli and Palestinian probes into war crimes in Gaza, and urged Israel to immediately open its border crossing with the Gaza Strip to alleviate the worsening humanitarian crisis there.
But the move, taken on Wednesday, was sharply criticised by Israel.
'Violation of international law'
"We find this resolution flawed and counterproductive," Yoel Mester, spokesman for Israeli mission to EU, said.
"While other players are striving to support the peace process and to start the proximity talks between Israel and Palestinians, it is regrettable that the European Parliament choses to concentrate on a highly controversial issue," he said.
But parliamentarians who supported the measure for the Goldstone report said they had taken a stand for human rights and respect for international law.
"For the first time, a resolution voted in the European Parliament acknowledges Israel's violations of international humanitarian law," Kyriacos Triantaphyllides, parliament member, said.
A key finding of the Goldstone report, published last September, was that Israel used disproportionate force in response to rocket attacks by Gaza-based fighters and failed to take adequate measures to protect civilians during its onslaught.
Wednesday's move is unlikely to help ties between the EU and Israel, which have been strained over several incidents in the past year.
In December, the EU accused Israel of trying to divide the bloc to stop it from passing a resolution calling for Jerusalem to be the shared capital of Israel and for a future Palestinian state.
The measure was adopted despite Israel's opposition.
The EU also has criticised Israel over its suspected role in the slaying of a Hamas operative in Dubai on January 19 this year and the killers' alleged use of forged EU passports.
Israel has been annoyed by a demand from Catherine Ashton, the EU's foreign policy chief, to be allowed to visit the Gaza Strip, which remains under Hamas control.
The European Parliament measure, passed by 335-287, said Ashton should "monitor actively the implementation of recommendations included in the Goldstone Report."
Richard Goldstone, a South African judge, recommended that both sides face possible prosecution before the International Criminal Court in The Hague if they failed to conduct credible, independent investigations within six months.
In January, the UN General Assembly gave Israel and the Palestinians five more months to finalise their own investigations into war crimes allegations during the conflict, in which 13 Israelis and almost 1,400 Palestinians were killed.
On Monday, Israel's Foreign Ministry said it would allow Ashton and Ban Ki-moon, the UN Secretary-General, into Gaza, an unusual step since Hamas took control of the strip in 2007.
In a related development on Wednesday, Ashton condemned Israel's plan to expand a Jewish neighborhood in disputed east Jerusalem, saying it should reverse the decision and "refrain from unilateral decisions and actions that may jeopardise the final status negotiations".
"The EU reiterates that settlements are illegal under international law," she said in a statement.
"They undermine current efforts for restarting peace negotiations ... and threaten to make a two-state solution impossible."