A Huawei signage is pictured at their store at Vina del Mar, Chile July 14, 2019. REUTERS/Rodrigo Garrido

WASHINGTON (Reuters) - Huawei Technologies Co Ltd, the Chinese company put on a U.S. blacklist because of national security concerns, secretly helped North Korea build and maintain its commercial wireless network, the Washington Post reported on Monday, citing sources and internal documents.

The Chinese telecommunications giant partnered with a state-owned Chinese firm, Panda International Information Technology Co Ltd., on a number of projects in North Korea over at least eight years, the Post reported.

Sources briefed on the matter confirmed the Commerce Department has been investigating Huawei since 2016 and is reviewing whether the company violated export control rules in relation to sanctions on North Korea.

Such a move would raise questions of whether Huawei, which has used U.S. technology in its components, violated American export controls to furnish North Korea with equipment.

Senators Chris Van Hollen and Tom Cotton said a statement the “revelation underscores (Huawei’s) ties to North Korea and its serial violations of U.S. law.”

They noted that a defense reauthorization bill under consideration in Congress contains new “provisions to better enforce sanctions on Pyongyang by making it clear that any company that does business with North Korea – like Huawei reportedly did – will face American sanctions.”

The United States put Huawei on a blacklist in May, citing national security concerns. The move banned U.S. companies from selling most U.S. parts and components to Huawei without special licenses but President Donald Trump said last month American firms could resume sales in a bid to restart trade talks with Beijing.

Huawei did not immediately respond to a request for comment, but said in a statement to the Washington Post it had “no business presence” in North Korea. It was not immediately possible to reach the Panda Group.

Huawei and Panda vacated their Pyongyang office in the first half of 2016, the newspaper reported.