The Trump administration has launched a dramatic attack on Huawei by requiring US companies to obtain licences to sell critical technology to the Chinese telecoms company.

The White House and Department of Commerce took dual actions on Wednesday that will effectively ban Huawei from selling technology into the American market, and could also prevent it from buying semiconductors from Qualcomm in the US that are crucial for its production.

Donald Trump issued an executive order declaring a "national emergency" in relation to threats against US telecommunications, in a move that authorised the commerce department to "prohibit transactions posing an unacceptable