"We're ruling nothing out and we have contingency planning for a wide range of scenarios," he said, speaking on Thursday ahead of a UN Security Council now under way to discuss how to ease Syria's humanitarian crisis.

Asked whether the options included a NATO-enforced no-fly zone without security council authorisation, he repeated: "We are not ruling out any options.

"We also have to be clear that anything like a safe zone requires military intervention and that of course is something that has to be weighed very carefully."

Fabius said Paris and London were in "complete unity ... on this point".

French Defense Minister Jean-Yves Le Drian has recently cautioned that closing Syria's airspace entirely would be tantamount to "going to war" but he urged the international community to consider backing a no-fly zone over parts of the unrest-torn country.

Talks of imposing a no-fly zone or a ground buffer zone in Syria have been put on the table allegedly to find a solution and to protect thousands of people fleeing the violence.

Following the news conference, the UN said any proposals to set up to secure safe zones raised "serious questions" and would need to be studied carefully.

"Such proposals raise serious questions and require careful and critical consideration," said UN Deputy Secretary-General Jan Eliasson.

The United Nations refugee agency said Thursday, August 30, 2012, that more than 220,000 people had fled Syria to seek safety and security in neighboring countries, and the refugees' "number is rapidly growing."

The UN also said Thursday, August 30, 2012, that over 2.5 million people are "in great need" of humanitarian assistance and protection inside Syria, and their "most pressing need" is water, sanitation, food, shelter, blankets and health care.