Washington (AFP) - The US Secret Service has bolstered security at the White House after a man was arrested making threats at one its checkpoints, a third such security scare in just over a week.

CNN reported that the man made a threat claiming he had a bomb in his car, and that he was immediately arrested and the car in which he was traveling seized.

President Donald Trump was away in Florida at the time

"On March 18, 2017 at approximately 11:05 pm, an individual drove a vehicle up to a Secret Service checkpoint located at 15th Street and E Street NW," a Secret Service spokesman said in the latest of a series of White House security concerns.

"Upon contact with the individual, US Secret Service Uniform Division Officers detained the individual and declared his vehicle suspicious. In accordance with proper protocols, Secret Service personnel increased their posture of readiness," he added.

Just hours earlier, a person was arrested after jumping over a bike rack in an apparent bid to reach the fence outside the White House, the Secret Service said.

The individual was detained immediately and criminal charges are pending, the agency said in a statement, without identifying the suspect.

A Secret Service official speaking on condition of anonymity said that person was not found to be carrying any weapons.

The arrest came about a week after a more serious incident that called into question security outside the White House.

Just before midnight on March 10, a man scaled three barriers outside the White House -- a perimeter fence, a vehicle gate and then another fence -- and walked around the grounds of the executive mansion for 16 minutes before being arrested.

That time Trump was inside the building.

- 'Total embarrassment' -

Republican Congressman Jason Chaffetz dubbed the incident "a total and complete embarrassment."

"(Homeland Security chief John) Kelly told me that this person was there on the ground for 17 minutes, went undetected, was able to get up next to the White House, hide behind a pillar, look through a window, rattle the door handle," the lawmaker told CNN.

According to the Washington Post, that man, who is from northern California, was carrying a backpack and two cans of mace.

The White House has seen a string of high-profile trespassing incidents in recent years.

In one notable incident in 2014, while Barack Obama was president, an army veteran described as mentally disturbed made it into the White House grounds, sprinted across the lawn and entered the building with a knife in his pocket before being tackled and arrested.

Secret Service personnel were also involved in an embarrassing scandal in Colombia when a dozen agents were found to have hired prostitutes during a 2012 presidential trip.

And just last week, a laptop was stolen from an agent in New York and remains missing, the agency said Friday, amid reports that the device contained floor plans of Trump Tower.

CNN -- citing law enforcement sources in New York -- said that though the computer was highly encrypted, it contained floor plans and other sensitive contents.

The Secret Service did not detail the contents of the laptop, but emphasized that such devices "contain multiple layers of security including full disk encryption and are not permitted to contain classified information," adding that an investigation was ongoing.

Trump resided in the luxury high-rise before moving into the White House. His wife Melania and youngest son Barron still live there.

The Secret Servicre, made up of some 6,500 people, is tasked with protecting the US president, former presidents and vice presidents, as well as foreign heads of state on official visits.