OTTAWA (Reuters) - Canada refused to offer any hints on Friday on the timing of a decision on a bid by China's CNOOC Ltd for energy company Nexen Inc..

"Whatever the date, appropriate notice will be given," Andrew MacDougall, a spokesman for Prime Minister's Stephen Harper, told Reuters by email.

Canada's industry minister must rule whether the $15.1 billion offer is of net benefit to Canada. The December 10 deadline can be extended, provided both companies agree.

(Reporting by David Ljunggren, writing by Cameron French; Editing by Janet Guttsman)