The proposed $35 billion merger between Didi Chuxing and Uber China is facing a potential regulatory barrier, according to Reuters.

China’s commerce ministry (Mofcom) said it had not received the application it would need before it could assess the merger. The ministry is one of the bodies in the Chinese state that rules on anti-trust matters.

“Mofcom has not currently received a merger filing related to the deal between Didi and Uber,” said a ministry spokesman.

“All transactors must apply to the ministry in advance. Those that haven’t applied won’t be able to carry out a merger” if they fall under the country’s M&A rules, he said.

Whether such a filing was necessary had been unclear as both firms are loss-making, as they fought aggressively against one another for market share.

However, the merger would create the overwhelmingly dominant force in China’s ride sharing market. Didi is already by far the country’s biggest player – the Reuters report pegs its market share at 87 per cent even before the merger with its smaller rival.

Neither Didi or Uber commented.