Britain, France and Germany have launched a fresh bid at the U.N. to end six weeks of violence in Gaza, after Israeli warplanes killed three top Hamas commanders, inflicting a heavy blow on the movement's armed wing.

The European initiative on Thursday came as fighting flared on the ground and an Egyptian-led effort to broker peace talks teetered on the verge of collapse.

Palestinian President Mahmud Abbas held talks with exiled Hamas leader Khaled Meshaal on Thursday as renewed fighting raged in Gaza following the collapse of Egyptian-brokered truce efforts.

The talks in Doha, where Meshaal is based, were hosted by Qatari Emir Sheikh Tamim bin Hamad al-Thani, a key backer of the Islamist movement which dominates Gaza, the Gulf state's QNA news agency reported.

Qatar, accused by a German minister of financing Islamic State (IS) jihadists, condemned on Thursday the group's beheading of U.S. journalist James Foley as a "crime against the principles of Islam".

The gas-rich nation's foreign ministry "expressed in strongest terms its condemnation of the killing of U.S. journalist James Foley at the hands of a criminal group," in a statement published by the official QNA news agency.

Interior Minister Nouhad al-Mashnouq has said he was not aware of the involvement of a regional country in the mediation to release the troops and policemen kidnapped by jihadists in the northeastern border town of Arsal earlier this month.

Al-Mashnouq told al-Akhbar newspaper published on Thursday that General Security chief Maj. Gen. Abbas Ibrahim is not in contact with any regional or Arab country in the efforts exerted at setting free the soldiers and Internal Security Forces members.

Israeli warplanes killed three top Hamas commanders in southern Gaza on Thursday, inflicting a heavy blow on the movement's armed wing after failing to kill its top military chief.

As the six-week war between Israel and Hamas raged on, leaving Egyptian mediated truce talks in tatters, warplanes pounded Gaza killing three members of the Islamist movement's armed wing, the Ezzedine al-Qassam Brigades.

Germany's development aid minister, Gerd Mueller, on Wednesday accused Qatar of financing the jihadist group Islamic State (IS) operating in Syria and Iraq.

"A story like this always has a history," he said in an interview with public broadcaster ZDF. "Who is financing these troops? Hint: Qatar."

Jihadists, who are holding Lebanese army troops and policemen captive, have reportedly announced conditions for their release despite the denial of Interior Minister Nouhad al-Mashnouq and mediators.

Al-Qaida linked al-Nusra Front members have said they would release one soldier or security forces member held captive earlier this month in return for two Islamists jailed in Lebanon, al-Akhbar daily said Wednesday.

Palestinian president Mahmud Abbas will travel to Doha on Wednesday and hold talks the next day with the emir of Qatar and Hamas exiled leader Khaled Meshaal, the Palestinian ambassador in Qatar said.

Negotiators in Cairo were pushing Israel and the Palestinians to put a decisive end to weeks of bloodshed in Gaza Monday as the clock ticked down on another temporary truce.

As the death toll in the war-torn Gaza Strip pushed over 2,000, Egyptian negotiators were pressing both sides to reach agreement before a midnight (2100 GMT) deadline which will mark the end of a five-day truce.

Prime Minister Tammam Salam revealed on Tuesday that he recently contacted Qatari and Turkish authorities to help Lebanon guarantee the safe release of the security personnel taken hostage by Islamist gunmen in the northeastern town of Arsal.

“Speaker Nabih Berri and I seem to have confluence on contacting Qatari and Turkish authorities to help the government ensure the safe release of the troops,” Salam said in comments published in As Safir newspaper on Tuesday.