Australia has blocked the potential multi-billion dollar sale of the country's biggest electricity network to two Chinese companies, citing national security reasons. Treasurer Scott Morrison did not discuss specific concerns Thursday when he announced his decision to reject bids from China's State Grid Corp and Hong Kong-based Infrastructure Holdings, which were seeking to lease a 50.4 percent stake in Ausgrid for 99 years. The network provides power for the state of New South Wales and its capital, Sydney. The sale would have earned the New South Wales government at least $7.6 billion. Morrison says the two companies have until next Thursday to appeal his decision. Australia's recent decision to sell the Port of Darwin to a Chinese company sparked a strong backlash over the sale of vital infrastructure projects to foreign countries.