The creation of a no-fly zone over Libya would require a clear legal basis and broad international support, William Hague stressed today.
The Foreign Secretary said it was "unacceptable" that Colonel Muammar Gaddafi was unleashing violence against the Libyan people, adding that he was "gravely concerned" about the potential impact of any escalation of that.
But he added that work by British and French diplomats on a United Nations resolution for a no-fly zone was a matter of "contingency planning".
"There must be a demonstrable need that is accepted broadly by the international community, as well as the strong international support that would come from that," he said at a press conference at the Foreign Office.
"There are examples of that already - the Gulf Cooperation Council statement is one example - but it has to have a clear legal basis, demonstrable need, strong international support, and broad support in the region and a readiness to participate in it.
"But clearly it is unacceptable that Col Gaddafi unleashes so much violence on his own people and we are gravely concerned about what would happen if he were to try to do that on an even greater basis."
Mr Hague said the Government would look at "other options as well" as circumstances required.
"At the moment there appears to be - it might not quite be a stalemate because there are military movements backwards and forwards - it seems that either side lacks the immediate power to overthrow the other," he said.
"What we call for is for Gaddafi to go, for people in Libya to be able to have the representative and broadly-based government they want, for that to be able to bring about the peaceful situation in Libya that Libyans want and that the whole world desires.
"But, of course, if that scenario changes, if it goes in other directions, well, then we have to look at other options as well, but I think we are not in that position yet."
Pressure was being increased on the Gaddafi regime by the UN Security Council as well as the contingency planning for a no-fly zone, Mr Hague said.
He added: "Those are the things we are engaged in now. Of course, it depends on how the situation develops what we might be called upon to do or decide to do later."
After former Liberal Democrat leader Sir Menzies Campbell publicly questioned his enthusiasm for the job of Foreign Secretary, Mr Hague insisted that he was committed to the post for "an extended period of time".
"These are historic and momentous events that are taking place," he said.
"I say to you very seriously that all of us who have taken on the job of shouldering responsibilities at this time will see those responsibilities through for an extended period of time in the face of any criticism or setbacks.
"That is certainly how I feel about it."