Shares in Chinese smartphone maker Xiaomi surged more than 10 percent in Hong Kong on Monday after a U.S. judge removed it from a blacklist that barred American companies from investing in it. 

The firm's stock price has been hammered since mid-January when Donald Trump, in his last days in office, included it in a group the White House considered a threat to U.S. national security. 

The move classified Xiaomi, which is among the biggest smartphone makers in the world, as one of nine "Communist Chinese military companies" that also included state oil giant China National Offshore Oil Corporation and popular social media app TikTok. 

But U.S. District Judge Rudolph Contreras ruled Friday that the Department of Defense and the Treasury "have not made the case that the national security interests at stake here are compelling."

He removed Xiaomi from the blacklist and suspended the investment ban after the firm appealed against the blacklisting. 

The news sent shares in the firm surging 12 percent in Hong Kong morning trade on Monday, having lost more than 40 percent since Trump's order.