The latest tally marked the smallest number of quarterly defectors since North Korean leader Kim Jong-un assumed power in late 2011.

Since the second half of 2015, North Korea has bolstered border control and set up high-tension wires around the Tumen River, which flows between the North and China to prevent more North Koreans from escaping the country, according to a report by the Korea Institute for National Unification (KINU).

Some experts said that China may have beefed up surveillance along the border with North Korea in an expression of its anger against Seoul and Washington's ongoing deployment of an advanced U.S. missile defense system.

China has sent scores of tanks into areas bordering North Korea in an apparent bid to strengthen border control, according to sources.

The Seoul government remained cautious about the reading of the latest tally.

"In the first two months of 2017, the number of North Koreans coming to the South fell on-year. But as those people rose in March from a year ago, it is hard to prejudge (what the data means)," a ministry official said.

The number of North Korean defectors surpassed the 30,000 mark in November last year.

Last year, the pace of annual growth of the North defectors picked up for the first time since 2011.

A rise in defections was largely attributable to Kim's move to strengthen his iron-fisted rule and the toughening of international sanctions, the government earlier said. (Yonhap)