The Sensex at the Bombay Stock Exchange rose 118 points, or 0.7 per cent, to 16,863 in opening trade, on Tuesday morning, on across-the-board buying by investors. Later, as regional markets firmed up, the Sensex gained further ground, to stand 265 points, or 1.6 percent in the green, and cross the 17,000 mark, at 17,011 in afternoon trade, a short while ago. Regionally, reversing initial losses, key stock indices in China, Singapore, Taiwan and South Korea were up by between 0.2 percent and 0.9 percent, today. But worries over the European debt crisis, following ratings agency, Standard and Poor's downgrade of Italy's sovereign debt rating capped gains. Elsewhere, the US Dow Jones Industrial Average had closed 0.9 per cent lower, overnight.