SEOUL • It has been an inauspicious return to crisis-plagued South Korea for former United Nations chief Ban Ki Moon, once the odds-on favourite to be the next president, who has been ensnared in a family corruption scandal and struggled with a sceptical press.

Mr Ban, 72, has been unable to capitalise on his much-anticipated homecoming after a decade as secretary-general of the UN in New York.

Since his return on Jan 12, he has cut a sometimes irritable figure in public and been pilloried for a series of perceived public relations gaffes - all without announcing any intention to run for president.

Now the United States has asked South Korea to arrest his brother, Mr Ban Ki Sang, on charges that he engaged in a bribery scheme to carry out the sale of a Vietnamese building complex.

The timing of the case could hardly be worse for Mr Ban Ki Moon, whose high international profile and clean image were expected to be assets when he returned to a nation reeling from a presidential corruption scandal.

President Park Geun Hye has been impeached by Parliament and stripped of her powers while a court decides her fate.

Mr Ban apologised on Saturday for family members who had caused public concern. "I have absolutely no knowledge of this case," he said in a statement.

However, a Realmeter poll released on Monday showed his support slipping from 22.2 per cent last week to 19.8 per cent, compared with 29.1 per cent for Mr Moon Jae In of the opposition Democratic Party.

The poll numbers are volatile and analysts say it is too early to count out Mr Ban, who has yet to affiliate himself with a party.

He has a team of politicians and former diplomats supporting him and has made several campaign-style appearances around the country since his return, pitching him in the full glare of the media spotlight.

On his arrival in Seoul, he took the airport express train instead of a limo, but did not know how to buy a ticket. He was pictured trying to insert two 10,000 won bills into the machine at the same time for a 7,500 won ticket.

"Couldn't you have treated it as something cute from a person who'd been in New York for a long time?" he protested at a meeting with voters and reporters in the southern city of Daegu.

Two days later, he visited a care home where he fed porridge to an old woman. He was criticised for wearing a bib when the old woman was not - and for feeding someone lying flat on their back.

He also dressed head to toe in protective gear to try out a disinfectant spray when most of those around him wore ordinary clothes, media said. And he was criticised for picking up a bottle of Evian mineral water from a convenience store before being told by an aide he should buy a local product.

Until recently, he had been tipped to run as a member of Ms Park's conservative Saenuri party. But being a Saenuri candidate looks far less attractive now because of the corruption scandal, and he has been seen as likely to join a new breakaway group from the conservative bloc, the Barun Party.

Kookmin University political science professor Hong Sung Gul said Mr Ban must be disappointed by his reception.

"That's what happens when there are high expectations and you don't come in with a clear and specific message," he said. "But it is too early to write off his campaign as being in serious trouble."

Mr Ban himself admitted on Monday to some "clumsy moments" and irritability since his return. "I was impatient and had passion for wanting to go and meet the people as soon as I could, so there were little mistakes," he told reporters. "I'll take it as a tough lesson learned and try to be better prepared."

REUTERS