Israel offered to help moderate Arab nations threatened by a lightning offensive by Islamic militants in Iraq, as the country's top diplomat met with US Secretary of State John Kerry on Thursday.

Israeli Foreign Minister Avigdor Lieberman told Kerry at a meeting in Paris that "the extremists currently operating in Iraq will try to challenge the stability in the entire Gulf region, first of all in Kuwait," a statement from the Israeli minister's office said.

"Israel could provide effective and reliable assistance to moderate Arab states who are dealing with extremists," it added, without going into specific details.

Just a few days after visiting Iraq, Kerry said it was "important that countries in the region stand together against the threat," according to a senior US official.

Asked about Lieberman's proposal, a State Department official said that it was "not raised with regard to the specific ISIL threat that is ongoing today."

"But Foreign Minister Lieberman did speak generally to the idea of a shared threat to all countries of the region from extremists."

Militants from the Islamic State of Iraq and Levant (ISIL) have captured a swathe of territory in northern Iraq in a lightning assault which is threatening to tear the country apart.

Kerry was holding a series of meetings with Middle East allies in Paris to discuss the crisis in Iraq after visiting both Baghdad and Arbil to press Iraqi leaders to unify against the dangers posed by ISIL.

The Sunni militants have overrun vast swathes of five provinces north and west of Baghdad, leaving more than 1,000 people dead and displacing hundreds of thousands.

The conflict also appears to be broadening with Iraqi Prime Minister Nuri al-Maliki confirming Syria's air force struck Sunni militants on the Syrian side of the Iraq-Syria border this week.

Lieberman said Israeli interests were converging with moderate Arab nations "with both sides dealing with the threat of Iran, world jihad and Al-Qaeda, as well as the spill-over of conflicts in Syria and in Iraq to neighbouring countries."

"Today, there is a basis for the creation of a new diplomatic-political structure in the Middle East," his office said in the statement.

But such a proposal is highly unlikely to find traction among Arab countries without any progress on the currently stalemated Middle East peace process.

Lieberman also handed Kerry an appeal from the parents of three kidnapped Israeli teenagers to meet with them. One of the youngsters is a dual Israeli-American citizen.

The teenagers are believed to have been kidnapped by Hamas militants, sparking a massive manhunt on the West Bank.

According to army figures, some 381 people have been detained in two weeks of searches for the teens who disappeared on June 12 while hitchhiking in the southern West Bank.

A State Department official told AFP that they have received and are "considering the request" for Kerry to meet the parents.

Kerry hosts Iraq talks with Mideast allies
Paris (AFP) June 26, 2014 - US Secretary of State John Kerry hosted urgent talks with Gulf allies and Jordan on Thursday to address the widening crisis in Iraq, where Sunni Islamic extremists have seized a swathe of territory.

Bringing together his counterparts from the largely Sunni nations of Jordan, Saudi Arabia and the United Arab Emirates, Kerry pressed home "that the threat of ISIL is not just to Iraq, it's to the region," a senior State Department official said.

The top US diplomat also briefed them on his visit this week to Baghdad and Arbil, in northern Iraq, where he sought to persuade fractious Iraqi leaders to unify to save the country which risks tearing apart in the face of the militant threat.

All the ministers present in Paris "expressed concern at the lack of inclusivity within the current government and the need for that to change going forward," the US official said.

Militants from the Islamic State of Iraq and the Levant this week seized the main border crossing from Iraq into Jordan, causing alarm in the Hashemite kingdom.

The oil-rich Sunni Gulf kingdom of Saudi Arabia has accused Iraq's Shiite Prime Minister Nuri al-Maliki of fuelling the crisis by marginalising the country's Sunni Arab minority.

Washington has been calling on the countries to use their influence with Iraqi leaders and Sunni tribes to try to press for unity, as well as to disrupt any private networks which may be acting inside their own countries helping or funding ISIL.

Kerry thanked the ministers for coming to discuss a "number of critical issues" at the talks held at the lavish US ambassador's residence. At one point he called US officials in Baghdad to get the latest update on the situation.

The ministers, each just accompanied by one aide, took off their jackets and sat outside in the warm Parisian sun huddling together for about 90 minutes.

Asked whether Kerry had discussed potential US air strikes on ISIL forces, another senior State Department official said he told the ministers that the US "was in the process of looking at potential targets, but at this point no decision has been made to take military action."

- Saudis ordered to defend territory -

Saudi Foreign Minister Prince Saud al-Faisal said that "all these issues... are of immense importance for our countries."

"And I think with the cooperation between the countries we can affect hopefully the situation in the Middle East."

ISIL aspires to create an Islamic state that straddles Iraq and Syria and the ministers were also to discuss the three-year Syrian conflict.

Kerry will fly to Saudi Arabia on Friday to discuss the turmoil in the Middle East with King Abdullah.

The Saudi monarch on Thursday instructed authorities in the oil-rich kingdom to take "necessary measures" to defend the country from jihadists battling the government in neighbouring Iraq.

The measures were not spelled out but decided during a security cabinet meeting chaired by the king and devoted to discussing developments in Iraq and their impact on Gulf Arab monarchies.