The two crew members on the F-15E fighter jet ejected to safety. One has already been recovered by US forces, who say they are in the process of rescuing the other.
It is understood that at least one of the crew members was initially rescued by rebel Libyan soldiers after ejecting from the aircraft.
The crashed plane was discovered by a Telegraph journalist reporting in and around Benghazi, the rebel-held city.
It is thought the F-15E fighter jet came to ground after suffering a mechanical failure.
The US military confirmed that one of its jets had crash landed but said that it had not been shot down.
Vince Crawley, a spokesman for the US military's Africa Command, said that one crewman had been recovered and one was "in process of recovery".
Both crew members suffered minor injuries.
Crawley said the crash occurred "overnight." He declined to give the location of the incident and also would not say how the rescued crewman was picked up.
This is the first coalition aircraft to have crash landed during the Libyan conflict following the third night of air strikes.
The developments comes after British ministers yesterday contradicted senior military commanders by suggesting that coalition forces in action over Libya can legitimately target Colonel Muammar Gaddafi.
The Chief of the Defence Staff, Gen Sir David Richards, flatly insisted that seeking to hit the Libyan dictator was not allowed under the terms of United Nations Security Council resolution 1973.
But after Defence Secretary Liam Fox suggested over the weekend that Col Gaddafi could be a "legitimate target", No 10 sources insisted it was legal to target anyone killing Libyan civilians.
The controversy blew up as Col Gaddafi's compound in Tripoli was hit in a second night of coalition air strikes aimed at suppressing the regime's air defences and command and control structure.
Following a meeting of the newly formed Libya subcommittee of the National Security Council, chaired by David Cameron, Gen Richards was adamant that it was not permitted to target Col Gaddafi.
"Absolutely not. It is not allowed under the UN resolution and it is not something I want to discuss any further," he said.
At a Ministry of Defence briefing, Gen Richards' spokesman, Major Gen John Lorimer, stressed that the international military intervention was in support of the UN no-fly zone.
"It is very clear that, in support of the United Nations Security Council, we are there to implement and enforce the no-fly zone," he said.
"The targets we are attacking are command and control facilities and the integrated air defence system. They are legitimate military targets."
Earlier however, Foreign Secretary William Hague refused to rule out an attack on the Libyan leader.
"I'm not going to speculate on the targets," he told the BBC Radio 4 Today programme. "That depends on the circumstances at the time."
Dr Fox also discussed the possibility at the weekend, although he stressed the need to avoid civilian casualties in any attack.
"Well, that would potentially be a possibility but you mention immediately one of the problems we would have, which is that you would have to take into account any civilian casualties that might result from that," he said.
"And at all times we are very careful to avoid that for its humanitarian reasons, but also for the propaganda reasons that it would provide for the regime itself."
He added: "There's a difference between someone being a legitimate target and whether you would go ahead with targeting."
James Arbuthnot, the Tory chairman of the Commons Defence Committee, said Mr Cameron had agreed in the House that the aim of protecting Libya's civilians could not be achieved without the removal of Col Gaddafi.
"We accept that the aim of the resolution is to protect civilians and not to change the regime," he told BBC Radio 4's The World at One.
"Nevertheless we won't be able to protect the civilians in my opinion – and obviously the Prime Minister's and that of most leaders of the countries in the region – while Gaddafi remains in place."
In a statement, a Ministry of Defence spokesman said: "We are not going to go into operational details on military targets.
"Our clear aim is to implement UNSCR 1973 – that means saving lives and protecting the civilian population of Libya."
The talk of targeting Col Gaddafi also appeared to alarm the Americans, with US Defence Secretary Robert Gates warning that it could undermine the cohesion of the international coalition supporting the no-fly zone.
"If we start adding additional objectives then I think we create a problem in that respect," he said.
"I also think it is unwise to set as specific goals things that you may or may not be able to achieve."
Shadow defence secretary Jim Murphy said Dr Fox's comment was "irresponsible in many ways" and could harm efforts to harness Arab opinion in favour of the military effort.
"I support the Government's decision on Libya but I think Liam Fox's comments are irresponsible in many ways," he wrote on his blog.
"His view that the aim of our military effort is to bring about regime change is outside what is a very broad UN resolution.
"It is wrong but also counterproductive at a time when we are trying to maintain a broad coalition, including Arab opinion, to talk in such a way.
"I agree with US Defence Secretary Robert Gates, who said, 'If we start adding additional objectives then I think we create a problem'.
"Gaddafi is a tyrant, but it is up to the people of Libya to decide what happens next in their country and not for any single foreign government.
"Our government needs to have one clear policy on this."
He confirmed that he was the Labour figure who told a Sky News reporter that Dr Fox should be "put back in his box".
The MoD would not be drawn on a report in London's Evening Standard newspaper that the cruise missile which hit Gaddafi's compound was fired by a British Trafalgar-class submarine.
"The MoD will not discuss targeting," a spokesman said.
International journalists, who were taken to the scene of a damaged administration block in the compound by Libyan officials, reported seeing smoke rising from the three-storey building and pieces of cruise missile scattered around the area.
About 300 Gaddafi supporters were said to have been in the compound at the time, but it is not known if any were hurt. It was not clear where Gaddafi was at the time of the attack.
Meanwhile, Downing Street published a note on the legal advice given by Attorney General Dominic Grieve which concluded there was "a clear and unequivocal legal basis for deployment of UK forces and military assets to achieve the resolution's objectives".
Coalition commanders were assessing the impact today of a second night of missile attacks and air strikes on Libyan targets.
RAF Tornado GR4 ground attack aircraft made the 3,000-mile round trip from their base at Marham, only to pull out of their bombing run at the last minute after civilians were reported in the target area.
Commanders said the Tornadoes would now be deployed to the Italian airbase of Gioia del Colle, where the Typhoon fighters are already stationed. Four Tornadoes were seen taking off from Marham earlier.
Gen Lorimer said: "We are satisfied that our attacks and those of our partners have been highly effective in degrading the Libyan air defence and command and control capability."