Two Canadian surveillance aircraft have been sent to the Libyan coast to help coalition forces keep ships from bringing weapons and mercenaries into the North African country.

The Auroras departed 14 Wing Greenwood in Nova Scotia and are in the midst of travelling to a military base in Trapani, Italy.

Defence Minister Peter MacKay announced the deployment plans on Thursday afternoon, saying that two CP-140 Aurora planes will soon be engaged in the "evolving" mission against Libyan leader Moammar Gadhafi.

NATO began patrolling Libya's coast on Wednesday, with the intention of cutting off the ability of ships that could be carrying weapons to reach shore. But it currently does not have enough vessels to patrol the entire coast.

MacKay said the planes will be used "to provide strategic maritime surveillance and support of the United Nations Security Council resolution 1973 and in particular in support of the arms embargo enforcement mission."

The Auroras will help "provide the Canadian Forces and the coalition with continuous presence over a vast theatre of operations" along the Libyan coast, he said.

Each is equipped with long-range sensors and can carry enough fuel to patrol the air for 17 hours.

In addition to the Auroras, Canada already has seven CF-18 fighter jets and a frigate, HMCS Charlottetown, involved in the UN-backed campaign to protect Libyan civilians against attacks from Gadhafi's forces.

MacKay said the deployment of the two surveillance planes will not affect the military's ability to conduct operations, or to provide search and rescue services in Canada.

Canadian fighter jets were recently on air-to-ground missions but didn't fire on any targets. However, earlier this week they attacked an ammunitions depot and drove back a convoy of tanks.

Currently, the U.S. is still leading the coalition operations in Libya, though MacKay said discussions are underway to develop "a revised command structure for operations."

NATO has agreed to command the naval blockade, MacKay said, but no decision has been made about changing command of the no-fly zone.

The international coalition has launched repeated air strikes and military barrages on Libya's military installations and ground troops loyal to Gadhafi.

The military offensive has helped temporarily repel Gadhafi forces from the rebel-hld city of Misrata, and has kept them from advancing on Benghazi, the centre of the rebel movement.

Meanwhile the rebel-held city of Ajdabiya has weathered a week-long siege by Gadhafi forces despite the coalition strikes.

MacKay said Canada currently has 435 military members taking part in the ongoing operations in Libya.

Canada's National Defence website indicates that the Canadian Forces have previously used Auroras in hundreds of patrol missions in the Persian Gulf.

With files from The Canadian Press and The Associated Press