Chinese network vendor Huawei has been refused permission by the US government to bid for a contract to work on the nationwide emergency network. A government spokesperson said that permission was refused due to national security concerns. The firm as now asked the government to elaborate on its reasons.

US Commerce Department spokesman Kevin Griffis explained in an e-mail to news agency Bloomberg that Huawei would not be taking part in the program “due to U.S. Government national security concerns”, although he declined to elaborate on the nature of those concerns or how the decision was reached.

Huawei has repeatedly seen efforts to expand in the country run into opposition from US authorities, who have cited alleged links to China’s military, which Huawei has denied. The company employs 1,500 workers in the country and said that it had spent $6.1 billion last year on goods and services.

“Notwithstanding that it is an ill-founded, ungrounded determination, it could have a chilling effect on our greater U.S. business activities and accountability needs to be defined appropriately,” said William Plummer, a Washington-based spokesman for Huawei.

He added that the company wants to know the statutory authority and regulatory regime under which the latest decision was made.