The Chinese engineer injured in a bomb attack in southern Pakistan has recovered and returned to the company's compound after medical treatment, a Foreign Ministry spokeswoman said on Tuesday.

Immediately after the incident on Monday, the Chinese embassy in Pakistan and the consulate general in Karachi, Pakistan's largest city, urged the Pakistan government to investigate the case as soon as possible, spokeswoman Hua Chunying told a regular news conference.

China has called on the Pakistani authorities to take measures to protect the safety of Chinese companies and staff, and Pakistan police are investigating the case, she added.

According to a report by Reuters, responsibility for the attack was claimed by a little-known separatist group based in the southern province of Sindh. The small roadside device exploded in a suburb of Karachi.