South Korea's President Yoon Suk-yeol has landed in trouble after disparaging remarks about the United States were caught on an open microphone.
Mr Yoon, a political novice who took office on 5 May, is in New York for the United Nations General Assembly and chatted on Wednesday with US President Joe Biden during a photo opportunity at the Global Fund where the US President had just pledged US$6 billion ($9 billion).
"How could Biden not lose damn face if these f***ers do not pass it in Congress?" Mr Yoon was caught saying to his aides afterwards in footage that went viral in South Korea.
A YouTube video of Mr Yoon's comments racked up over two million views just hours after it was posted, and "f***ers" became the number one trending topic on Twitter in South Korea on Thursday.
"The president's words and actions are the national dignity of the country," one YouTube commenter wrote.
Mr Yoon's crude comments appear to refer to Mr Biden's drive to increase US funding to the Global Fund, which would require congressional approval.
The Global Fund is focused on fighting HIV, tuberculosis and malaria.
The US is South Korea's key security ally, with Washington stationing about 27,000 troops in the country to help counter nuclear-armed North Korea.
Allegations denied
Mr Yoon's office has denied the incident, with spokeswoman Kim Eun-hye saying Mr Yoon had "no reason to talk about the US or utter the word 'Biden'".
Speaking at a press briefing in New York on Thursday, Ms Kim claimed that Mr Yoon did not actually say "Biden" but a similar-sounding Korean word, and that he was referring to South Korean, not US, lawmakers.
One ruling-party parliamentarian suggested the television station that first reported the hot-mic comments should be prosecuted.
"MBC should gravely be held accountable for its report that has damaged the irreplaceable US-Korea alliance," wrote MP Yoon Sang-hyun on his Facebook account.
But online, many expressed doubt about the government's response.
"It is utterly shameful and embarrassing for our kids that our presidential office has come up with such an excuse," one commentator wrote on YouTube.
"I've listened to it 10 times now. It's 'Biden' for sure," another added.
Mr Yoon, a former prosecutor, has made what analysts describe as a string of unforced errors during his first months in office, which is typically a honeymoon period for new presidents in South Korea.
At one point, his approval rating dropped to 24 per cent, although it has since inched up to 32 per cent.
His predecessor, Mr Moon Jae-in, enjoyed approval ratings of about 70 per cent at the same stage in his term, polling data showed, and Mr Yoon started work with 52 per cent of people polled thinking he was doing a good job.
The crude comments come just days after Mr Yoon's office was forced to defend his decision to skip paying respects to Queen Elizabeth II's coffin lying in state, allegedly due to "heavy traffic".
In August, he was also criticised for a chaotic official response to US House Speaker Nancy Pelosi's visit to South Korea, where she landed after a contentious stop in Taiwan.
Mr Yoon's critics were swift to seize on his latest alleged gaffe. Mr Yoon's "foul language tarnishing the US Congress caused a major diplomatic mishap," said Park Hong-keun, floor leader of the opposition Democratic Party.
