Gen. Walter Natynczyk says establishing a no-fly zone in the skies over Libya would be a major military offensive, as a top U.S. senator urged allies to start planning such an operation.

"I don't think you can understate the severity of a no fly zone scenario," Natynczyk told CTV's Question Period on Sunday, describing the process involved as a major military operation.

"Before you can fly and ensure the security of a region you have to dismantle the air defences on the ground. That includes the runways and the aircraft on the ground, and the command and control facilities on the ground. That is a major military operation; it is an offensive operation."

U.S. Democratic Sen. John Kerry wants Western forces to start planning a no-fly zone, but said it would require an international agreement to enforce.

Speaking to CBS's Face the Nation on Sunday, Kerry said he didn't think it would necessarily have to be a military intervention.

Republican Sen. John McCain told ABC's This Week that a no-fly zone would signal to Gadhafi that the U.S. government is "serious" when it says embattled leader Moammar Gadhafi must step down. "And also, it would be encouraging to the resistance, who are certainly outgunned from the air."

But President Barack Obama and defence officials are hesitant to push for a no-fly zone, arguing that such a move is akin to a declaration of war.

"Lots of people throw around phrases of 'no-fly zone' and they talk about it as though it's just a game, a video game or something. Some people who throw that line out have no idea what they're talking about," White House chief of staff William Daley told NBC's Meet the Press.

Despite the mixed signals coming out of the United States, British Defence Minister Liam Fox said talks of a no-fly zone are at "the very early stage of contingency planning." Fox told BBC Radio that NATO defence ministers will be discussing all options at a meeting in Brussels later this week.

Canada was last involved in a no fly zone operation in Kosovo during the 1990s. The Canadian Forces have three dedicated aircraft posted near the North African nation in order to assist with the extraction of Canadians and other refugees, as well as more than 100 ground support units, including medical personnel, in the country.

HMCS Charlottetown left from Halifax for the Mediterranean several days ago and is expected to arrive off the coast of Libya by Wednesday.

Natynczyk said the warship will be posted in the region in order to provide humanitarian relief and not for military purposes.

"The situation is so volatile and uncertain, not only in Libya but in the whole region. The entire region has changed within the last six weeks, so from a Canadian Forces standpoint we want to be sure that Canada has sufficient flexibility and options," Natynczyk said.

He added that he could not speculate on what future missions may be necessary.

Earlier this week, Britain sent special forces into Libya to extract a group of oil workers. Natynczyk also said he would not comment on what Canada's special forces may be asked to do, but said reports he has received do not suggest Canadian nationals are in a position where they would need similar help.

During his interview with Question Period, Natynczyk also discounted reports that Canadian aircraft landed last week at the airport in Tripoli without permission from Libyan authorities.

"In every occasion we have received the go-ahead from the tower," he said. "One of the challenges we have had is who represents the authority on the ground. In the chaotic days earlier this past week it was the control tower allowing us to land on the ground."