BEIJING — China’s Commerce Ministry said a preliminary review of Qualcomm Inc.’s $44 billion purchase of NXP Semiconductors has found “issues that are hard to resolve.”

A spokesman for the ministry, which is China’s main antitrust regulator, said the review is still going on. Initially, the review has turned up “related issues that are hard to resolve, making it difficult eliminate a negative impact,” the spokesman, Gao Feng, said Thursday.

China is the last major government yet to approve the pending deal between the San Diego-based Qualcomm , a major supplier of smartphone chips, and NXP , a Dutch semiconductor maker.

Gao’s comments are the Chinese government’s first public remarks about the review since Beijing and Washington began engaging in tit-for-tat threats of a trade war. In a sign of Beijing’s displeasure, the Commerce Ministry slowed its review of the deal in recent weeks, according to people familiar with the matter.

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China has reservations about Qualcomm’s $44 billion deal for NXP