BEIJING, March 8 (Reuters) - China announced tariffs on over $2.6 billion worth of Canadian agricultural and food products on Saturday, retaliating against levies Ottawa introduced in October and opening a new front in a trade war largely driven by U.S. President Donald Trump's tariff threats. The levies, announced by the commerce ministry and scheduled to take effect on March 20, match the 100% and 25% import duties Canada slapped on China-made electric vehicles and steel and aluminium products just over four months ago. By excluding canola, which is also known as rapeseed, and was one of Canada's top exports to the world's No.1 agricultural importer prior to China investigating it for anti-dumping last year, Beijing may be keeping the door open for trade talks.