EU ambassadors were holding emergency talks this afternoon to discuss the deaths of a reported 15 people on boats off the coast of Gaza by Israeli forces.
Britain is being represented at the gathering of experts on the EU Political and Security Committee, by Tim Barrow for what was described as "an exchange of views".
One official said it was impossible to predict what stance, if any, the 27-nation meeting would make.
Meanwhile, European Parliament official said there were no Euro-MPs aboard the boats heading for Gaza which were intercepted by Israeli forces.
But the leader of the centre-right European People's Party in the European Parliament, Joseph Daul, commented: "We are shocked with the Israeli military operation that resulted in the loss of so many lives and the number of persons injured. We extend our sincerest sympathies to the families of those killed and injured.
"Many questions have to be answered, such as what is the explanation for such an excessive use of force? Was there a life-threatening resistance to justify the use of live ammunition?"
Martin Schulz, leader of the Socialist Group in the European Parliament, said: "The use of lethal force against civilians on these ships is unacceptable. Israel has crossed a line in the military action shown on our television screens today.
"We now demand safeguards for the people who have been taken into captivity by Israeli forces. The international community must make its revulsion clear to the Israeli authorities."
Socialist MEP Veronique de Keyser, who returned on Friday from a delegation to Gaza, said: "We must now require Israel to lift the blockade of Gaza completely. This incident has taken us to a point of no return."
The leader of the Liberal Democrats in Europe, Guy Verhofstadt, said the facts of the incident remained unclear.
"A full and independent inquiry into the events that led up to the incident is vital to establish the truth and prevent further recrimination or retaliation," he said.
"At the root of the issue is the ongoing human tragedy on the ground in Gaza, currently exacerbated by the blockade of goods and aid to the needy. This policy helps no-one and is counterproductive to the cause of building a sustainable peace in the region. It needs to change."
He added: "Whether intentional or not, the humanitarian aid flotilla has drawn international attention once again to the problem facing Israel and the international community in resolving one of the worlds most intractable conflicts."