Foreign Secretary William Hague today insisted that Muammar Gaddafi's regime was "weakening all the time" in the face of Nato's military campaign.
But he warned it was "impossible to say" how long it would take to unseat the dictator.
Mr Hague also said his preference was for Gaddafi to be charged with crimes against humanity, rather than killed in an airstrike or exiled.
Interviewed on Sky News' Murnaghan programme, Mr Hague said: "Time is on our side, not on his side. The position of the Gaddafi regime is weakening all the time.
"They have been losing important battles ...
"We have to have the patience and persistence to see this through to success, and remember that the time pressure is on the other side, on the Gaddafi regime."
He added: "We will have the staying power to implement the UN resolution and see this through to success."
Asked whether he would prefer Gaddafi to be killed, surrender, or go into "negotiated exile", Mr Hague replied: "Clearly we would like to see him answer charges before the international criminal court, so if I had to choose one of your options that is what i would like to see.
"But if he escaped to some place that was not party to the international criminal court we would not necessarily be able to prevent that."