BEIJING - China had urged Nigeria to immediately investigate an armed attack in which two Chinese engineers were killed, a Foreign Ministry spokesman said Thursday.

Two engineers from the China Civil Engineering Construction Corporation were shot dead by unknown armed forces on Wednesday on their way to a construction site in north Nigeria's state of Yobe.

"The Foreign Ministry has instructed the Chinese embassy in Nigeria to deal with the incident immediately. The embassy lodged representations with the Nigerian side," spokesman Hong Lei said at a daily news briefing.

The embassy also urged the Nigerian government to take concrete measures to ensure the safety of Chinese nationals in the country, Hong said.

The attack was the third involving Chinese working in Nigeria in the last month. A cook working for a Chinese construction company was killed in the city of Maiduguri in north Nigeria's state of Borno on Oct 8.

A Chinese construction worker was shot dead in the same city on Oct 19.