Authorities say a Pakistani guard shot and wounded two Chinese nationals working in a textile mill in the southern port city of Karachi, but the attack was not related to militant violence.

Two Chinese nationals were shot at and injured on Tuesday in Pakistan's commercial hub of Karachi, police and hospital officials said, after a string of attacks that spurred Beijing to demand tougher security for its citizens.

A private security company guard posted at a textile mill in Karachi opened fire and seriously injured two Chinese nationals following a quarrel on Tuesday morning, according to a senior city police officer as well as the Foreign Office in Islamabad.