FACTBOX-Canada has blocked small number of foreign investments

Dec 7 (Reuters) - Canadian authorities approved the acquisition of Nexen Inc by China's CNOOC Ltd on Friday and the purchase of Progress Energy Resources by Malaysia's Petronas after months of anxiety over the fate of foreign investments in Canadian resources.

In the past, the government has blocked a few proposed investments by foreign companies under the Investment Canada Act. The only rejections have been delivered by the current Conservative government, and only since 2008.

Here are the transactions that have been turned down:

- In May 2008, Ottawa blocked on security grounds a $1.325 billion offer by U.S. rocket-maker Alliant Techsystems Inc for a space robotics and satellite technology unit of real-estate data and space technology company MacDonald Dettwiler and Associates Ltd.

- In November 2010, it rejected BHP Billiton's $39 billion bid for Potash Corp, the world's largest fertilizer maker, citing the need to be "careful stewards" of Canada's natural resources. Premier Brad Wall of Saskatchewan, the province in which Potash Corp is based, opposed the takeover.

- In October 2012 it made an initial decision blocking Malaysian state oil firm Petronas's C$5.17 billion ($5.23 billion) bid for gas producer Progress Energy, giving it 30 days to make new representations as to why the deal would be of net benefit to Canada. On Friday it approved the deal.

($1=$0.99 Canadian) (Reporting by Randall Palmer; Editing by Peter Galloway)