Mumbai, February 1: The rupee weakened by 9 paise to 63.67 against the US dollar in opening trade at the inter bank foreign exchange market ahead of the budget today. A strong dollar in overseas markets weighed on the Indian currency, a currency dealer said.

Yesterday, the rupee had ended 2 paise higher at 63.58 against the US dollar. Foreign investors withdrew a net Rs 136 crore from stocks yesterday, according to provisional Foreign Portfolio Investment data.

Meanwhile, the benchmark BSE Sensex rose by 171.38 points, or 0.47 per cent, to 36,136.40 in opening trade today.