A Washington state senator has been arrested and charged in Hong Kong with possession of an unregistered firearm, according to his office.
Jeff Wilson, a Republican from the Washington city of Longview, was arrested after landing at the Hong Kong International Airport on Saturday.
He was travelling with his wife for a five-week holiday in Southeast Asia, his website said.
Wilson appeared in court Monday to face the charge of possession of arms without a license and was granted bail, Hong Kong's public broadcaster RTHK reported.
"It was an honest mistake, and I expect the situation to be resolved shortly," Wilson said in a statement.
The statement added that the gun was not registered in the financial hub but is registered in Washington.
Wilson said he was unaware of the unloaded weapon in his bag when he went through security at the Portland, Oregon airport, and it was not noticed by the baggage screeners.
When asked for comment, the Port of Portland referred the request to the Transportation Security Administration (TSA), responsible for passenger screening at the airport.
A TSA spokesperson said the agency "takes this situation very seriously and is currently investigating the circumstances", NBC News reported.
The spokesperson said officers at the Portland airport had detected 43 firearms at security checkpoints so far this year.
Following Monday's hearing at the Shatin Magistrates' Courts, Wilson surrendered his travel documents and is set to appear at the West Kowloon Magistrates' Courts, The Standard newspaper reported.
Hong Kong's Customs and Excise Department declined to comment due to the ongoing legal proceedings.
Carrying an unlicensed firearm in Hong Kong can result in a fine of up to 100,000 Hong Kong dollars (£11,145) and a maximum sentence of 14 years, although the Magistrates' Courts typically grant a maximum two-year sentence for such cases, as per the judiciary's website.
Wilson's website said he discovered the weapon mid-flight from San Francisco to Hong Kong and promptly informed customs authorities upon landing.