SEOUL (AFP) - A woman pretending to be a former South Korean first lady was arrested on Friday (Nov 23) on suspicion of swindling a politician out of nearly US$400,000 (S$550,000), a report said.

Claiming to be late president Roh Moo-hyun's widow Kwon Yang-sook late last year, the fraudster allegedly persuaded the then mayor of Gwangju to transfer her 450 million won (S$546,000), saying she needed it for her daughter and promising to repay it quickly.

At the time, Mr Yoon Jang-hyun, a member of the Democratic party of both Roh and current President Moon Jae-in, was seeking the organisation's nomination for a second term as leader of the southern city.

Corruption allegations are commonplace in South Korean politics, and its last two presidents Lee Myung-bak and Park Geun-hye are both serving prison sentences for graft.

Roh himself committed suicide by jumping off a cliff in 2009 after he was questioned over a corruption case involving Kwon.

Her alleged impersonator texted around 10 prominent figures in Gwangju in December, but Mr Yoon was the only one to pay out, Yonhap news agency reported.

Friday's arrest came after a man was held earlier this week on charges of pretending to be close to a presidential aide in charge of managing Mr Moon's supposed slush funds.

The 65-year-old allegedly persuaded his victim to hand over 550 million won, promising him some of the proceeds of bars of gold bullion he claimed were stashed in a secret warehouse.

Mr Moon - who previously worked as a top aide to Roh - last month warned South Koreans against people impersonating his family or staff.

"If you meet anyone who calls for money, citing the names of presidential relatives or Blue House officials, consider all of them as swindlers and report them immediately to the authorities," he said in a statement.