The rupee on Monday breached the 63-level in intra day trading for the first time against the US dollar in Foreign Exchange market on higher demand for dollar, particularly from oil importers.The currency tumbled by 1 rupees 65 paisa to 63 rupees 30 paisa, despite a series of measures by RBI and government to check the rupee slide.Meanwhile, the BSE benchmark Sensex fell by 291 points to end at over 4-month low of 18,307 on Monday, as the investor sentiment had taken a hit with rupee touching new lows.