This satellite image, released by 38 North on Nov. 24, 2021, shows North Korea's Yongbyon nuclear complex, north of Pyongyang. Yonhap

North Korea has readied an underground nuclear test tunnel at its Punggye-ri site and a test blast could take place sometime between Oct. 16 and Nov. 7 if the regime decides to go ahead with it, South Korea's spy agency was quoted as saying Wednesday.

The National Intelligence Service (NIS) gave the assessment during a closed-door briefing to lawmakers of the parliamentary intelligence committee, citing a window of time between October's National Congress of the Chinese Communist Party and November's U.S. midterm elections, according to briefed lawmakers.

"The NIS has reported that Tunnel No. 3 at Punggye-ri has been completed and the possibility of a nuclear test has risen," Rep. Yoo Sang-beom of the ruling People Power Party told reporters.

Punggye-ri is where the North conducted all six of its nuclear tests to date.

On foreign media reports on the public appearance of a 9-year-old girl assumed to be North Korean leader Kim Jong-un's daughter, the NIS said it is "unlikely" the girl is Kim's daughter Ju-ae, according to Yoo.

Rep. Youn Kun-young of the main opposition Democratic Party also said that the NIS has identified an unidentified woman who has been reported to be closely accompanying the North's leader, as a former drummer at Pyongyang's all-women Moranbong Band, named Hong Yun-mi.

The NIS also reported that Hong appears to be an aide to Hyon Song-wol, a vice department director of the Central Committee of the Workers' Party of Korea, according to Youn.

The NIS also reported that leader Kim exchanged eight personal letters with Chinese President Xi Jinping and it is difficult to believe North Korea's announcement it has completely eradicated the COVID-19 pandemic, referring to the North's recent efforts to vaccinate people across its border region.

Kim appears to be showing no signs of health issues and returned to weighing between 130 and 140 kilograms, lawmakers said, citing the NIS. (Yonhap)