NATO Secretary General Anders Fogh Rasmussen called on Israel to immediately release those people and boats still held after its deadly storming of a Gaza aid flotilla.
Mr Rasmussen said: 'I offer sincere condolences to the families of all victims and condemn the acts which have led to this tragedy.
'As a matter of urgency, I also request the immediate release of the detained civilians and ships held by Israel.
The emergency meeting of the North Atlantic Treaty Organisation, was requested by Turkey.
Yesterday's operation angered Turkey and it recalled its ambassador to Tel Aviv.
Mr Rasmussen said: 'I would like to express my deep regret over the loss of lives and the other casualties resulting from the use of force during the incident involving the convoy sailing to Gaza.
'I add my voice to the calls by the United Nations and the European Union for a prompt, impartial, credible and transparent investigation into the incident.'
According to NATO officials all 28 member states supported the UN statement during the 90-minute NATO meeting.
US Secretary of State Hillary Clinton has urged all parties to be careful in their responses to the attack.
She said: 'I think the situation from our perspective is very difficult and requires careful, thoughtful responses from all concerned.'
The UN Security Council yesterday condemned the acts that led to the killing of at least nine people by Israeli commandoes aboard the Turkish Mavi Marmara ship.
In a formal statement following more than ten hours of closed door discussions in New York, the UNSC called on Israel to conduct an impartial investigation and to release the ships and civilians being held.
Four of the five permanent members of the UN Security Council have called for Israel's blockade of Gaza to be lifted, but the US did not do so.
During the UN session, Turkish Foreign Minister Ahmet Davutoglu said Israel had committed a serious crime.
At least four Turks were among nine people killed in the Israeli raid on aid ships bound for Gaza, a Turkish diplomat said.
Israeli radio has said 480 activists captured in the raid are being detained, while 48 others would be expelled.
It claims its troops came under attack as they intercepted the vessel in international waters.
The campaigners say the soldiers opened fire without provocation.
Former President of Ireland Mary Robinson has described the Israeli embargo on Gaza, and its treatment of Palestinian citizens, as 'one of the greatest human rights violations'.
The former UN High Commissioner for Human Rights said the blockade was illegal, inhumane and counter-productive.
Mrs Robinson said that if ongoing talks involving the US Middle East envoy George Mitchell do not lead to an outcome, the US should come forward with a proposal for resolving the problems in the region.
She added that the EU must show a concerted political will, and do much more in terms of resolving the conflict.
With international criticism of his country mounting, Israeli Defence Minister Ehud Barak said he hoped common sense would prevail.
Mr Barak said he regretted the loss of life, but hoped the majority of nations would understand that Israel was in a difficult position because of the presence of the militant group Hamas, which controls Gaza.
