VANCOUVER, British Columbia, Oct 9 (Reuters) - Canada will consider applying a national security test to foreign takeovers of Canadian firms but will not apply it to deals already under way, Industry Minister Jim Prentice said on Tuesday,

Prentice signaled the new rules he will be examining this autumn would not apply to a proposed C$5 billion ($5.1 billion) takeover of oil and gas producer PrimeWest Energy Trust PWI_u.TO by Abu Dhabi National Energy Co TAQA.AD.

"Transactions that are already in the works will proceed under the terms of the current legislation. Changing the rules in the middle of the game is not how this country does business," he said in the prepared text of a speech he was delivering in Vancouver.

($1=$0.98 Canadian)