The Indian rupee strengthened by 18 paise to 72.42 against the US dollar in early trade on Friday tracking positive domestic equities. At the interbank foreign exchange, the domestic unit opened at 72.46 against the dollar, then inched higher to 72.42, registering a gain of 18 paise over its previous close. On Thursday, the rupee had settled at 72.60 against the US dollar.

Most Asian currencies have started flat to marginally stronger against the US dollar this Friday, Reliance Securities said in a research note. Traders will track the Reserve Bank of India's reserves data that will be released after market hours. Meanwhile, the dollar index, which gauges the greenback's strength against a basket of six currencies, rose 0.09 per cent to 90.04.