Police in Pakistan say gunmen have shot and killed a former police officer who was fired over the 2011 killing of five Chechen women in the southwestern city of Quetta.

Naseebullah Khan, a senior police officer in Quetta, says two gunmen riding a motorcycle opened fire on Fazlur Rehman outside a car showroom on Sunday.

Rehman and another police officer said they mistook the Chechen women for terrorists and opened fire on them. Both were fired, and the other police officer was shot dead in 2013.

The Pakistani Taliban claimed Sunday's attack, saying it was revenge for the killing of the women.