By Gul Yousafzai

Quetta, PAKISTAN (Reuters) - Gunmen shot dead four paramilitary officials in Pakistan's western city of Quetta on Wednesday, police said, a day after four policemen were killed in a region that is to host a $46 billion China-Pakistan economic corridor.

Police said the officials of the paramilitary Frontier Corps were patrolling in their official vehicle when they were attacked. Two officers died on the spot while another two succumbed to their injuries in hospital.

"Four of our soldiers have been killed in a terrorist attack," Khan Wasey, the spokesman for the paramilitary force said on Wednesday. No militant group claimed responsibility.

Quetta is the capital of Baluchistan province, rich in resources and at the heart of multi-billion-dollar energy and infrastructure projects which China and Pakistan are planning along a corridor stretching from the Arabian Sea to China's Xinjiang region.

The province, the poorest and least developed in Pakistan, has suffered nearly a decade of separatist violence against the government and non-Baluch ethnic groups.

Baluch activists and human rights groups accuse the military of carrying out a campaign of kidnapping, torture and extrajudicial killing of suspected separatists, and a security crackdown has severely limited freedom of movement.

(Writing by Mehreen Zahra-Malik; Editing by Mark Heinrich)