President Moon Jae-in's approval rating dropped to the lowest level in over four months last week, a poll showed Monday, amid controversies over a corruption investigation into former President Lee Myung-bak's aides, policy confusions over cryptocurrencies and the formation of an inter-Korean joint women's hockey team for the Winter Olympics.

In a weekly survey by Realmeter, 66 percent of 2,509 people surveyed said they approved of the way the president managed state affairs, down 4.6 percentage points from a week earlier.

The reading marked the lowest since 65.6 percent tallied in the third week of September, the local pollster said in a press release. The latest survey had a margin of error of 2 percentage points.

Moon's approval rating slipped to 67.1 percent in the first three days of last week but further slipped to 64.8 percent Thursday when the former president claimed in a nationally televised press conference that the ongoing prosecution investigation was a political retaliation aimed at him.

The incumbent president returned fire Friday, saying he was "infuriated" to hear Lee's accusation. His approval rating still continued to drop, reaching 64.4 percent.

Those who disapproved of Moon's way of managing state affairs came to 29.3 percent of the total, the highest since 29.4 percent tallied in the third week of September, according to Realmeter.

The ruling Democratic Party too suffered a significant setback with its approval rating falling 3.3 percentage points from a week before to 48.3 percent last week.

The main opposition Liberty Korea Party, on the other hand, gained 1.2 percentage points to 18.1 percent.

The approval rating of the liberal People's Party came to 5.9 percent, up 0.8 percentage point, while that of the splinter Bareun Party came to 5.7 percent, up 0.4 percentage point. (Yonhap)