The rupee weakened 15 paise to 66.96 against the US dollar in early trade at the Interbank Foreign Exchange today following increased demand for the American currency from banks and importers.The rupee had lost 5 paise to end at 66.81 per dollar yesterday on fresh demand from banks and importers for the UScurrency despite firm domestic equity markets.Meanwhile, the benchmark BSE Sensex rose further by 88 points to 28,212 in early trade.