President Donald Trump on Thursday called on U.S. telecommunications companies to boost their work to build faster 5G wireless "and even 6G" communications networks, saying they were lagging and at risk of being left behind other countries' efforts.

"American companies must step up their efforts, or get left behind," Trump said in a pair of tweets.

"I want the United States to win through competition, not by blocking out currently more advanced technologies," he added, although he did not explain what blockage the president was referring to. Representatives for the White House could not be immediately reached for comment.

The Trump administration has been seeking ways to speed the deployment of faster wireless communications systems that could help a number of industries.

Last year, the Federal Communications Commission Chairman (FCC) moved to eliminate regulatory barriers to 5G deployment by capping local fees and requiring faster application reviews.

The Republican president's administration has also been warning other countries against adopting 5G systems from Chinese telecommunications company Huawei Technologies Co Ltd, citing security concerns.