Image caption Canada's Foreign Minister Lawrence Cannon says his goverment is doing everything it can

An aircraft sent to rescue Canadian citizens from Libya left Tripoli without any passengers on board, after failing to find any Canadians waiting at the airport.

The majority of the Canadians registered with the embassy in Tripoli had said they wanted to leave.

However, a government source offered no explanation as to why the plane left carrying only the crew.

The source defended Canada's efforts to evacuate its citizens.

Tens of thousands of foreigners have been exiting the country by any means possible following a violent crackdown on protesters by Libyan leader Muammar Gaddafi.

Of the 344 Canadians registered with the embassy, 213 have said they want to leave.

The evacuation plan has hit several snags, and Canada has struggled to get charter planes to land in the volatile area to pick up their stranded nationals.

One flight was cancelled after the charter's insurers wouldn't provide cover for the mission.

It is unclear why this plane left empty, but Foreign Affairs spokeswoman Lynn Meahan said that dangerous conditions on the ground played a part.

She explained that the plane could not stay long on the ground, and that there were no other citizens from "like-minded countries" who needed the flight.

Canadian Defence Minister Peter MacKay blamed the incident on confusion.

"That has to do with co-ordination on the ground, ensuring that people are aware that an exit is available to them," he said.

Foreign Minister Lawrence Cannon said on Thursday that nearly 200 Canadians had been, or were about to be, evacuated on planes and ships arranged by other nations.