The White House dog Major has bitten again, just days after returning from training in Delaware following a similar incident earlier this month, APA reports citing BBC.
A spokesman for First Lady Jill Biden said that "out of an abundance of caution" an individual was seen by medical staff before returning to work.
Major is the younger of the Bidens' two German Shepherds and the White House's first ever rescue dog.
"He's a sweet dog," President Joe Biden has said.
Michael LaRosa, Mrs Biden's spokesman, said of Monday's incident: "Major is still adjusting to his new surroundings and he nipped someone while on a walk."
CNN reported that a National Park Service employee was bitten on the South Lawn and had to stop work to receive treatment. the National Park Service has not responded to CNN's request for comment.
Both Major and Champ, the Biden's 13-year-old dog, were moved to the Biden family home in Wilmington, Delaware, after the first biting incident on 8 March.
Anonymous sources told CNN at the time that Major had been jumping, barking and charging at White House staff and security.
President Biden said Major was acclimatising to so many new people around him. "You turn the corner and there's two people you don't know at all and they move, and he moves to protect," he told ABC's Good Morning America.
He went on to say: "Eighty-five per cent of the people [at the White House] love him. All he does is lick them and wag his tail. But... I realise some people, understandably, are afraid of dogs to begin with."
The Bidens adopted Major, who is now three years old, as a puppy from Delaware Humane Association in 2018. Champ had already spent some time in the White House as a younger dog, when Mr Biden was vice-president, before moving in permanently in January this year.