The Rupee weakened by 13 paise to 64.57 against the US Dollar in early trade on increased month-end demand for the American currency from importers and banks.

Forex dealers said the US Dollar's gain against other currencies overseas and a lower opening of the domestic equity market put pressure on the Rupee.

The Rupee had appreciated 18 paise against the American currency to end at a one-week high of 64.44 on 26 May, buoyed by stocks that soared to life highs.

Meanwhile, the benchmark BSE Sensex retreated from record highs by falling 158.31 points, or 0.51 per cent, to 30,869.90 in opening trade on Monday.