Huawei is thought to be ahead of other 5G equipment providers around the world, including European Union companies such as Ericsson and Nokia, in being able to install networks. Also, it has traditionally been a cheaper provider of technology.

Mr. Trump and other critics contend that a 2017 Chinese law could be used to force Huawei to hack its customers through preinstalled “back doors” into the network’s software, on behalf of Beijing.

The European report sounded some related concerns. “In particular, as 5G networks will be largely based on software, major security flaws, such as those deriving from poor software development processes within equipment suppliers, could make it easier for actors to maliciously insert intentional back doors into products and make them also harder to detect,” it found.

Abraham Liu , Huawei’s vice president for Europe, has said his company does not and will not use back doors to spy on customers.

“In the past, we have never planted any back door, and we are committed not to do anything like this, forced by any government, including U.S. government, Chinese government or any other government. We are committed to this,” he said in a recent interview.

The report presented on Wednesday could pave the way for the European Commission, the executive arm of the European Union, to recommend that its member states take additional security measures when procuring 5G networks.

The commission is expected to publish a “toolbox” of measures that countries can take to mitigate the risks, but it can’t force them to comply. Officials hope that by publicizing the risks and proposing ways to address them, countries that take a lax approach to security will be pushed into action by their citizens.