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.

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.

Authorities in Pakistan said Tuesday that a local security guard at a factory in the southern port city of Karachi shot and injured two Chinese nationals, the third attack this year in the country targeting workers from China.