Sri Lankan rupee ended 0.09% weaker at 175.90/176.00 per dollar, compared with Friday's close of 175.75/85, as importer demand for the greenback outpaced the dollar selling by banks. The rupee is up 3.81% so far this year. The central bank left key interest rates unchanged on July 11 as expected, after cutting them in May to support the economy as tourism and investment plummeted in the wake of deadly suicide bombings in April. Foreign investors bought a net 1.22 billion rupees worth of government securities in the week ended July 17, but the market has seen a year-to-date net foreign outflow to 18.46 billion rupees, the central bank data showed.