London Metal Exchange tin is poised for further gains as supply concerns in Indonesia and Bolivia persist, a broker notes. News Friday that Bolivian President Evo Morales has nationalized Swiss Glencore International's Vinto smelter, which produces 12,000 metric tons of tin a year, is boosting sentiment, he adds. Also the arrest of top officials at PT Koba Tin on Saturday on charges of illegal mining will likely add to gains, he says. LME tin trades is last bid at $12,250/ton, just down from Friday's high of $12,350/ton.