Mumbai: Ahead of the crucial referendum in Britain over the country's continuity in the European Union, key Indian equity indices opened flat on Thursday after ending lower the previous day in what was a volatile day of trading. The sensitive index (Sensex) of the BSE, which had closed on Wednesday at 26,765.65 points, opened at 26753.20 points. Immediately after, it was trading at 26,796.78 points, up 31.13 points, or 0.12 per cent. At the National Stock Exchange (NSE), where the 51-scrip Nifty had closed at 8,203.70 points, the opening bell was at 8,201.15 points. Thereafter, the index was ruling at 8,211.50 points, up 7.80 points, or 0.10 per cent. In other Asia-Pacific markets, the mood was mixed. While Australia's S&P/ASX, Japan's Nikkei and Hong Kong's Hang Seng gained marginally, the Shanghai Composite and South Korea's Kospi saw some declines in early trade. On Wednesday, Indian indices were range-bound amid volatility and heavy selling pressure. The markets got some respite after the government approved a new textiles package and the reserve price for spectrum auctions, among other decisions. Consequently, the Sensex gained some ground, but yet closed closed lower at 26,765.65 points, down 47.13 points or 0.18 per cent. The same was the case with Nifty, which ended 6.20 points or 0.20 per cent lower at 8,203.70 points. "Indian markets ended a lackluster session lower on Wednesday as investors exercised caution ahead of Thursday's all-important UK-wide referendum to decide on the country's future in the European Union," Angel Broking said in an analysis ahead of the opening bell on Thursday. "The US markets finished slightly lower on Wednesday, as polls showed the outcome of a UK referendum on whether to leave the European Union remained too close to call, a day ahead of the vote," it said. Investors were also disappointed by US Federal Reserve Chairperson Janet Yellen's comments on the prospects of jobs growth in the world's largest economy during her testimony to the US Congress late on Tuesday. "European markets ended Wednesday's session in positive territory, extending their winning streak to four sessions,"said the brokerage with similar investor sentiments as in other global markets.