The Indian rupee slumped 9 paise to 73.18 against the US dollar in opening trade on Thursday tracking strengthening of the American currency in the overseas market. Market participants remained vigilant ahead of Reserve Bank of India (RBI) monetary policy meeting outcome scheduled to be announced on Friday, forex traders said.

At the interbank foreign exchange, the domestic unit opened lower at 73.17 against the dollar, and lost further ground and touched 73.18, registering a fall of 9 paise over its previous close. On Wednesday, the rupee had settled at 73.09 against the US dollar. Most Asian currencies have started mostly flat to marginally stronger against the US dollar this morning and could lend support, Reliance Securities said in a research note.