Targeting Muammar Gaddafi and his military high command is permissible under the broadly drawn terms of the UN security council resolution, according to many international lawyers.

Regime change – the ultimate desire of most countries supporting the motion – is not, however, an aim specified in any of the 29 points of the UN text.

If it occurs, it will be as a byproduct of international intervention.

The key phrase in UN resolution 1973 – "to take all necessary measures ... to protect civilians and civilian-populated areas under threat of attack" – allows states participating significant latitude in deciding what is militarily possible.

The ambiguities created by such loose phrasing may even have been intentional.

"Sometimes these UN resolutions are [deliberately] not clear," said Anthony Aust, a former legal adviser to the UK mission to the UN who helped draft the Kuwait resolution in 1990. "They are ambiguous because it's the only way to avoid a veto."

Philippe Sands, professor of law at University College London, believes the Libyan leader is at personal risk.

"The authorisation of 'all necessary measures' is broad and appears to allow the targeting of Gaddafi and others who act to put civilians 'under threat of attack', words that go beyond the need to establish a connection with actual attacks," he wrote in the Guardian last Friday.

Malcolm Shaw, professor of international law at Leicester University, said: "Anything that supports Libyan jets – including the military command structure, airfields and anti-aircraft batteries – would be legitimate."

But, he cautioned, not all Libyan government sites could be hit: "I wouldn't think that blowing up the finance ministry in Tripoli would be authorised."

A political split over interpretation of the UN resolution already seems apparent, with Britain contemplating direct attacks on the Libyan leader on the grounds that he is behind the orders to attack civilians in Benghazi, Misrata and other rebellious cities.

Asked about killing Gaddafi, the defence secretary, Liam Fox, told BBC Radio: "It would potentially be a possibility. We are very careful to avoid [civilian casualties] for humanitarian reasons, [and] for the propaganda reasons that it would provide for the regime itself."

The foreign secretary also failed to deny that Gaddafi might become a target.

William Hague said he would not "get drawn into details about what or whom may be targeted", adding: "I'm not going to speculate on the targets ... That depends on the circumstances at the time."

But the US defence secretary, Robert Gates, appeared to take a more restrictive view of the terms of the resolution.

"The one thing that there is common agreement on are the terms set forth in the security council resolution," he said. "If we start adding additional objectives then I think we create a problem in that respect.

"I also think it is unwise to set as specific goals things that you may or may not be able to achieve."

The government is due to publish a summary of the legal advice on the UN-sanctioned Libyan operation written by attorney general Dominic Grieve later. It will be followed by a Commons debate and a vote on the military intervention.