Pilkington has had a preliminary takeover approach from Japan's Nippon Sheet Glass which may lead to a bid of about £2.1bn. Nippon, which already owns 20% of Pilkington, said it may make a cash offer for the remaining shares but said discussions were at an early stage. Pilkington shares surged 20% after it revealed details of the approach.Pilkington's financial position has improved in recent years, making it more attractive to would-be buyers. Last year it raised its shareholder dividend for the first time in a decade after boosting profits & sales. Nippon manufactures glass for buildings, cars, trains & IT products. "Nippon Sheet Glass confirms that it has made an approach to the board of Pilkington which may or may not lead to a cash offer for the Pilkington shares it does not already own," the company said in a statement to the London Stock Exchange. Analysts have put a bid value of about £2.1bn on Pilkington. Media reports have suggested that building firm Saint-Gobain, currently fighting a battle to buy British plasterboard maker BPB, is also interested in acquiring Pilkington. However, any bid from the French firm would face scrutiny from the competition authorities. Pilkington is a global manufacturer, with factories in 24 countries. Its shares were up 26 pence, or 20.5%, at 152.75p by late afternoon.