Two US Secret Service agents, who were on duty to protect President Donald Trump's grandson, are reportedly under investigation for taking selfies with the eight-year-old boy while he was sleeping.

A source with knowledge of the matter told Mother Jones that the agents were under probe for abandoning their post while charged with protecting the boy and not for criminal behaviour.

The incident happened last week when the two agents were driving the child from West Chester County, New York to Manhattan. The agents started taking selfies when Donald Trump III was sleeping in the car.

According to the report, the child was "freaked out" when he woke up. After reaching home he told about the experience to his mother Vanessa Trump, who in turn shared it with Donald Trump Jr.

The news immediately reached to management at the Secret Service and the two agents were ordered to report to Secret Service Office of Responsibility in Washington DC.

A spokesperson for the Secret Service confirmed in a statement to Mother Jones that an investigation was underway.

"The US Secret Service is aware of a matter involving two of our agents and one of our protectees. Our Office of Professional Responsibility will always thoroughly review a matter to determine the facts and to ensure proper, long-standing protocols and procedures are followed. The Secret Service would caution individuals to not jump to conclusions that may grossly mischaracterize the matter."

This development comes after an intruder was able to get into the outer perimeter of the White House grounds and got close to the north portico of the White House.

US Secret Service officials
Two US Secret Service officials are under investigation for taking selfiesReuters