DOHA (AFP) - The US ambassador in Doha on Thursday (June 9) formally apologised to Qatar after a video was posted online showing laughing American soldiers stationed in the Gulf allegedly insulting the emirate's flag.

Dana Shell Smith took to Twitter to apologise and called on the US military to investigate the incident after having been summoned by Qatar's foreign ministry.

"I have presented my apology to the government of Qatar and instructed the US military command to investigate the incident and take disciplinary action," she said on social media.

"My dear followers, please be assured that those soldiers were making fun of themselves and not the state of Qatar." The ambassador, who has served in Doha for the past two years, added that Qatar was a "staunch ally and an old friend".

The video shows a male and female soldier in fatigues standing in front of US and Qatari flags.

The pair are shown joking and laughing, saying they are being filmed at an "unknown dislocation".

The male soldier then says they are "in a place called ummm", and points to the Qatari flag.

The woman soldier repeats the word "ummm".

It is not clear when or where the video was filmed.

The foreign ministry also took to Twitter to say it was seeking answers from the Americans over the actions of the soldiers.

The ambassador "was asked for an explanation of the contents of that video", it said.

Qatar, where insulting its flag is a serious offence, hosts the largest American air base outside of the United States.

Al-Udeid base, home to around 10,000 military personnel, is used as a hub by the US for its air strikes against the Islamic State jihadist group in Syria and Iraq.