Whitehall officials said that the “same assets” that are currently waging air strikes on Col Gaddafi’s regime and its forces would be unleashed on the rebels should they take revenge on towns and populations that have so far remained under Col Gaddafi’s control.

It is the most explicit warning yet that the international coalition enforcing United Nations 1973 resolution has not written a blank cheque to the rebels as they launch offensives against the regime in Misurata and eastern Libya. But officials said the National Transitional Council (NTC), which represents the rebel movements had given repeated assurances that they would not seek to punish government sympathisers in the aftermath of victory.

“We will protect civilians by all means necessary while the mandate is in force – that applies to everybody,” a government official said.