Canada and the United States agreed Wednesday that hijacked aircraft that land in their territories will not be permitted to take off again.

The first international agreement of its kind is in keeping with the national policies of both countries, based on the belief that the ground is the safest place for the passengers of a hijacked aircraft.In the joint declaration, the two governments agree that "except under extraordinary circumstances, they will not allow hijacked aircraft which have landed in their territory to take off again."

A State Department spokesman said, "This is another step in our common fight against terrorism. It will help to deter hijackings by not permitting terrorists to move an aircraft lookingf for a sympathetic government or shopping for concessions."

The spokesman added, "We hope that this no-takeoff policy will receive the broadest possible application among the countries of the world."

The agreement was worked out in a series of discussions beteeen Secretary of State George Shultz and Canadian foreign minister Joe Clark.