The number of heavy debtors in South Korea has surged nearly 48 percent over the past three and a half years, a report said Tuesday, amid low interest rates and eased government property rules.

As of the end of June, 1.18 million people in the country had a debt service ratio of 100 percent or higher, up 47.5 percent from the end of 2014, according to the report from the office of National Assembly Speaker Chung Sey-kyun.

The number had been on a steady rise since 2013, reaching 800,000 at the end of 2014 and breaching the one million mark last year.

The DSR, published by the Bank for International Settlements, reflects the share of income used to service debt. It's regarded as a reliable early warning indicator for systemic banking crises.

The report is based on data from credit appraiser NICE Investors Service, which cover borrowers from local banks and non-bank lenders, excluding those pronounced defaulters or with no credit rating.

The sharp increase was ascribed to a prolonged period of low interest rates and the government's easing of real estate regulations, which analysts said prompted more households to borrow money beyond their means.

Chung called for urgent measures to tackle the issue. "Given the large number, the government should lose no time in coming up with measures to stop them from lapsing into default."

Meanwhile, the overall DSR for South Korean debtors came to 35.7 percent as of the end of June, compared with 31.3 percent at the end of 2014.

According to NICE Investors Service, South Korea debtors totaled 18.57 million as of end-June with their combined debt reaching 1,439 trillion won ($1.26 trillion). (Yonhap)