China’s transport minister said on Monday that ride-hailing companies like Didi Kuaidi and U.S. firm Uber Technologies Inc [UBER.UL] subsidizing discounts and supplementing driver wages was competitively unfair and not sustainable.

Those subsidies would not be sustainable in the long-term, said Yang Chuantang, speaking to reporters on the sidelines of China’s annual parliamentary session.

Companies like Didi Kuaidi and Uber are spending billions of dollars in heated competition, using investors’ money to fund discounts for users and drivers on their apps.