In 2016, Bank of Ceylon and People's Bank had credit growth of 30 to 32 percent while private banks have reduce the rate below 20 percent, he said.
Sri Lanka ended the year with private credit growth of around 21.9 percent in 2016, he said.
Coomaraswamy said the regulator wanted to better understand where the growth was coming from, though it did not want to influence individual commercial decisions of banks.
Credit at state banks may be growing partly due to funding contractors who were building roads, he said.