SEOUL, South Korea - South Korea's spy agency believes that North Korean leader Kim Jong Un's powerful uncle may have been dismissed from his posts last month and that two of his aides were executed, two lawmakers said Tuesday.

The lawmakers said they were told by South Korea's National Intelligence Service that Jang Song Thaek has not been seen publicly since then, indicating he may have been sacked.

There was no official word from North Korea on Jang's fate, and it was not possible to independently confirm the claim.

Jang has reportedly been purged in the past, only to return to power. He has held a slew of top posts and is married to Kim Jong Un's aunt, Kim Kyong Hui, the younger sister of late leader Kim Jong Il.

He was seen as a powerful influence as young leader Kim Jong Un consolidated power after his father Kim Jong Il's death in December 2011. Jang walked by Kim Jong Un's side as a hearse carried Kim Jong Il's body through Pyongyang, and over the last two years has appeared standing just behind his nephew at public events.

NIS wouldn't confirm the two lawmakers' details about Jang, which came in a closed-door intelligence briefing. One of the lawmakers, Jung Chung-rae, said the NIS didn't tell him how it obtained the information.

The other lawmaker, Cho Wonjin, said the spy agency reported that North Korean authorities were investigating corruption allegations involving Jang's aides and that they had been executed.

Jang was last seen in North Korean media on Nov. 6.

South Korean intelligence officials have erred previously in predicting changes in the secretive North, and senior North Korean officials occasionally disappear from state media reports and then reappear.