The Philippines’ DMCI Holdings Inc said on Monday its nickel mining units are laying off hundreds of workers and putting plans to ramp up production on hold, as a government crackdown has begun to take its toll on the beleaguered sector. DMCI’s Berong Nickel Corp will lay off over 300 seasonal workers in the coming weeks while its Zambales Diversified Metals Corp has already let go of more than 100 personnel, the conglomerate told the Philippine Stock Exchange.