Beijing has expressed deep concern about the latest economic espionage allegations targeting Chinese nationals in the United States, a case that observers say highlights growing economic friction between the two countries.

China is seeking further details and will work to safeguard the rights and interests of its nationals, Foreign Ministry spokesman Hong Lei said on Wednesday.

Hong's remarks followed the announcement that the US has charged six Chinese nationals with stealing mobile phone technology from two US chipmakers where some of them worked. A 32-count criminal indictment says the six were acting on behalf of universities and companies controlled by the Chinese government.