The number came down to 5.14 in May last year before tumbling to the low 4-point range in recent months, the poll showed. 

Another 10-scale indicator put the popularity of China as a foreign nation among South Koreans at 4.31 in January, slightly higher than 4.2 a month earlier, the poll also said. 

It was also a drop from the highest point of 5.54 posted in November 2015.

The grimmer results come as South Korea and Beijing are entangled in diplomatic tension over the plan to bring the Terminal High Altitude Area Defense system into South Korea to guard against North Korea's missile threats. The plan was announced in early 2016.

In retaliation of the deployment, which China says compromises its security interests, the country has banned South Korean entertainers from appearing on Chinese TV programs and targeted South Korean goods in China.

"China's protests over the plan to deploy THAAD on the Korean Peninsula are affecting South Korea's public sentiment," the institute said in a related report. "If China's hard-line measures continue it may further worsen South Koreans' public perception of China."

The report also showed shrinking support for the deployment plan among South Koreans, mainly due to the public's distrust of the government's policy-making process. 

The rate of support for the deployment peaked at 73.9 percent in February 2016, but has steadily come down to reach 46.3 percent as of November, according to the report.

The most frequent reason behind opposing the deployment was distrust of government decisions, followed by worsening relations with China.

"The change of public opinion showcased how domestic politics and a lack of trust in the president and government affect (public sentiment) about diplomatic policies," the report said, referring to Park's recent impeachment over a influence-peddling scandal.

Polls cited in the report were conducted on 1,000 adults aged

19 or older over the phone. They have a 95-percent confidence level with plus or minus 3.1-percent error. (Yonhap)