Acting on a tip-off, the Border Security Force (BSF) and Directorate of Revenue Intelligence (DRI) seized over 31 kg of heroin in Punjab's Ferozepur sector on Thursday, BSF officials said.The seizure - the highest single seizure in Punjab's border belt this year - was made in the area of border outpost Barreke in Ferozepur sector, over 300 km from here.Two smugglers from Punjab's border belt were apprehended in the joint operation by the BSF troopers and DRI officials. They have been identified as Parkash and Angrej Singh, aged 20 and 24 years respectively.A 9mm pistol, four magazines and 61 rounds of ammunition were also recovered from the smugglers, said BSF DIG R.S. Kataria.Punjab shares a 553-km international border with Pakistan. The entire border is fenced with electrified barbed wire.