The International Atomic Energy Agency (IAEA) says it will open an investigation into Israel's alleged use of depleted uranium during its 22-day offensive in the Gaza Strip.
Wednesday's announcement came after Arab nations sent a letter to Mohammed ElBaradei, the IAEA director-general, asking the UN agency to investigate whether the controversial munitions were used in the war, which left more than 1,300 Palestinians dead.
Depleted uranium is added to munitions because its density allows them to penetrate armour more easily.
It is thought that the dust left at blast sites after the weapons have hit could pose a health risk, but a definitive link has not yet been proven.
"We are circulating the letter to member states and will investigate the matter to the extent of our ability," Melissa Fleming, an IAEA spokeswoman, said after the UN agency received the letter from the Saudi Arabian ambassador.
The exact course of action will be decided after member states have been consulted, the UN agency said.
Israel has been criticised by human rights groups and foreign officials over its suspected use of a number of weapons during its aerial, naval and ground assault on the Palestinian territory.
The Israeli army says it has launched an internal investigation into the use of white phosphorus, a highly incendiary substance that can burn away flesh to the bone.
On Wednesday, Israel's Haaretz newspaper reported that the inquiry would focus on the alleged firing of about 20 phosphorus shells around the northern town of Beit Lahiya by Israeli paratroopers.
Amnesty International, a London-based human rights group, has said that its use in Gaza's densely populated urban neighbourhoods was a "war crime".
International law does not ban the use of white phosphorus used to create smoke screens to cover troop movements or illuminate targets, but human rights groups have said that its use could be illegal in civilian areas if "all feasible precautions" were not taken.
Amnesty and Human Rights Watch, along with the United Nations relief agency in Gaza, have said there is widespread evidence of Israel's use of the controversial chemical during the Gaza war.
Israel has refused to confirm whether white phosphorus was used in the territory, but said that all weapons it used were legal under international law.
Haaretz reported that the Israeli military fired a total of 200 white phosphorus shells during the three-week Gaza offensive.
There have also been accusations that the Israeli military used Dense Inert Metal Explosive (Dime) weapons in urban areas causing horrific abdominal and leg injuries.
When detonated, a Dime device expels a blade of charged tungsten dust that burns and destroys everything within a four-metre radius.
The European Union said on Wednesday it had received assurances from Israel that it will allow humanitarian aid through to the Palestinians in Gaza.
Karel Schwarzenberg, the Czech foreign minister and the meeting's chairman, said at a joint news conference after the meeting, that Tzipi Livni, the Israeli foreign minister, had reassured the EU that "everything will be done from the Israeli side to have an effective humanitarian aid in the Gaza Strip".
David Miliband, the British foreign secretary, said the talks produced a "strong'' discussion at which the Europeans insisted Israel must make it possible for humanitarian aid to reach the residents in Gaza.
Bernard Kouchner, the French foreign minister, said the 27 EU member states "were all united" in calling for Israel to open Gaza's borders.
For her part, Livni said she convinced the Europeans that having a "durable and sustainable ceasefire also means a full cessation of the smuggling of weapons'' into Gaza.
One of Israel's stated aims of their offensive was to stop weapons being smuggled into the Gaza Strip.
However, Al Jazeera on Wednesday received footage apparently showing the rebuilding of weapons smuggling tunnels into the strip.
Mark Regev, the spokesman for the Israeli prime minister, told Al Jazeera: "We said we didn't want Hamas to re-arm when this is over ... But what we've got in place, which we didn't have before this campaign, is a broad international coalition ... who are committed to making sure Iranian missiles don't reach the Gaza Strip."
Regev said this would be ensured by more intense border security between Gaza and Egypt and stepping up efforts to intercept rockets on transport routes from Iran to the Gaza Strip.
Meanwhile, Khaled Meshaal, the political leader of Hamas who is in exiled in Damascus, said on Wednesday that his organisation had been victorious during the offensive by Israel.
"We achieved our aims by forcing the enemy to halt its aggression and to withdraw," he said.
"But two more battles are left to win: to lift the blockade and open the crossing points [with Gaza], especially at Rafah [in Egypt] which is our gateway to the world."
Meshaal also said that Israel should begin to talk to Hamas and accused Mahmoud Abbas's Palestinian Authority, which controls the West Bank, of abandoning "the resistance in the face of the Israeli occupation".