Hwang Pyong-so and Kim Won-hong, the bureau's chief and deputy chief, were reportedly singled out in what was described as the first official inspection of the agency in two decades.
North Korean officials said Friday the regime would continue its nuclear buildup as long as South Korea and the United States continued to engage in joint military exercises.
The South Korean spy agency told the lawmakers that the North Korean investigation of the military political bureau is continuing, and is spearheaded by senior Workers' Party official Choe Ryong Hae, who was the military's top political officer before Hwang.
Asked to elaborate on the punishment, the lawmaker said that the NIS is still trying to figure it out. He is visiting as President Xi Jinping's special envoy, according to Chinese and North Korean state media, but no other details about his itinerary or whether he will meet with North Korean leader Kim Jong Un have been announced.
The bureau is seen as an influential military institutional as it leads the crucial personnel management of other military bodies such as the Ministry of People's Armed Forces, which was once headed by Choe.
The NIS also reported that the North has been focusing on forestalling a possible negative impact of the tightening worldwide sanctions on public sentiment.
Three shot dead in protests against Uhuru's Supreme Court win
The election went ahead and Kenyatta won by a landslide, though voting did not take place in a number of opposition districts. Already, opposition supporters have trooped to the streets to protest against the Supreme Court's decision.
North Korea "has banned any gatherings related to drinking, singing and other entertainment", the NIS, South Korea's spy agency, revealed during a parliamentary briefing Monday, according to Yonhap News Agency.
In response to North Korea's test of an intercontinental ballistic missile that can theoretically strike parts, if not most, of the continental US and the regime's detonation of a staged thermonuclear bomb, the global community imposed crippling sanctions on the rogue regime, severely restricting both imports and exports and forcing countries around the world to cut ties with the North.
South Korean intelligence officers are also monitoring the North for signs of new missile launches to ratchet up the threats against the USA under the guise of space development. "We forecast that depending upon North Korean leader Kim's determination, a nuclear test is possible any time", the agency said.
He said the country was "ready" for new sanctions and dismissed the possibility of North Korea being added to a list of countries that sponsor terrorism.
As to the possibility of another nuclear explosion, the NIS said there are now no signs of an imminent test.
Moreover, the NIS said that Tunnel 3 of the North's Punggye-ri nuclear test site is now available for a test, while the North has recently resumed construction on Tunnel 4 at the same facility.