The Pakistani Taliban has attacked buses carrying navy officials in Pakistan's largest city, killing four people and wounding 56 others.

The roadside blasts took place roughly 15 minutes apart on Tuesday in different areas of Karachi, a southern port city that is Pakistan's economic heart.

Tehreek-e-Taliban spokesmen claimed responsibility for the attack by telephone from undisclosed locations. 

Police said the bombs targeting the buses in two different parts of Karachi were remote controlled.

A junior naval officer and a civilian female doctor were among those killed in the twin blasts, Commander Salman Ali, a spokesman for the Pakistan navy, said.