The Border Security Force has recovered four kg heroin along the India-Pakistan border in Punjab's Amritsar sector, an official said on Sunday.The heroin, which is valued at Rs 20 crore in the international market, was seized in Uddhar Dhariwal area of Amritsar sector, BSF Deputy Commandant N.P. Negi said.BSF troopers heard a sound of something being thrown near the border fence.It is believed that smugglers from Pakistani side had thrown the packets containing heroin on the Indian side of the fence.The BSF has recovered over 161 kg of heroin along the border belt in Punjab so far this year.