Chinese regulators are seeking additional concessions from Qualcomm Inc. before approving its proposed purchase of NXP Semiconductors NV, further complicating the long-delayed deal and possibly adding to trade tensions between China and the U.S.

The proposed acquisition would have substantial impact on the technology industry and may have negative affects on the market, a spokesman for China’s Ministry of Commerce said. Bloomberg News reported in March that Mofcom wanted more protection for local companies, which are concerned the combined entity would extend Qualcomm’s patent licensing business into areas like mobile payments and autonomous driving.

“The authority has talked with Qualcomm about how to reduce the negative impact on the market and has conducted market tests using the remedy plan from Qualcomm. An initial investigation shows Qualcomm’s plan can hardly solve relevant problems,” said Gao Geng, the spokesman.

He said Qualcomm withdrew its application for approval from Mofcom this week and, according to a statement the ministry posted on its website later, the application has been re-submitted.

“We will continue to conduct a fair investigation and review according to the rules, including anti-monopoly law,” he said, adding a decision is unlikely to come soon because it needs a “large amount of time to investigate, collect evidence and analyze.”

The comments come amid increasing trade tensions between the world’s two largest economies. President Donald Trump has threatened tariffs on $150 billion in Chinese imports for alleged violations of intellectual property rights, while Beijing vowed to retaliate on everything from American soybeans to planes.

This week, the U.S. imposed a seven-year ban on China’s ZTE Corp. that prevents the telecommunications-equipment maker from buying technology from American suppliers, a devastating blow to its global aspirations. Mofcom responded by saying it’s “ready to take necessary steps” to protect domestic companies.

China, the world’s largest importer of semiconductors, is seeking to reduce its dependence on foreign technology and build its own world-class industry. The country’s top listed chip companies, including Semiconductor Manufacturing International Corp. and Hua Hong Semiconductor Ltd., surged Wednesday on anticipation Beijing may increase its already substantial support for domestic companies.

The NXP transaction is crucial for Qualcomm after it fought off a hostile takeover bid by Broadcom Inc. that forced its management to give commitments for future business expansion and earnings that it’ll now have to deliver. Qualcomm aims to lessen its dependence on a smartphone market that is slowing and where competitors and customers are increasingly fighting to overturn its dominance.

Qualcomm’s largest-ever transaction was announced more than a year ago and the San Diego-based chipmaker had told investors it would be closed by the end of 2017.