(BSS/AFP) - US President Donald Trump`s Qatari-gifted Air Force One was delayed on the tarmac Wednesday after an emergency inflatable slide accidentally deployed, raising fresh questions over the safety of the jet.

Trump -- who was preparing to travel to a Republican Party convention in Dallas from Joint Base Andrews -- had to wait in his helicopter before being able to board the plane following the incident.

The 80-year-old then told reporters that inspectors were checking one of the Boeing 747`s inflatable slides used for emergency evacuations.

"They`re checking the slide over here, and I think it`s going to take 15 minutes," Trump said on the tarmac before boarding.

But a person briefed on the situation later told AFP that "military personnel accidentally triggered the slide."

The plane`s safety has been the subject of recurring questions, and the issue came to a head during a recent dramatic incident in Turkey, where Trump secretly switched to a different aircraft amid security concerns.

Asked by an AFP reporter Wednesday whether Trump was sure the jet was safe, Trump responded: "Yeah I am, or I wouldn`t be on it."

Upon arrival at Joint Base Andrews near Washington, Trump remained on his helicopter for an unusually long time before finally boarding Air Force One, the name given to an airplane carrying the US head of state.

This gave reporters time to observe an inflatable slide deployed on the right side of the jet, as well as the former presidential plane being repositioned from its hangar onto the tarmac, with its boarding bridges extended.

The current Air Force One eventually took off and landed in Texas, where Trump is to speak at a Republican convention in a bid to rally his party ahead of November`s midterm elections.

"As the president has said, the slide was checked out to make sure everything works perfectly," White House Communications Director Steven Cheung said in a statement to AFP, adding that Trump would "deliver his much-anticipated speech to a raucous and sold-out crowd."

- Security -

The Qatari plane, repainted in a red, white and blue livery chosen by Trump, was last in the spotlight in July, when Trump decided at the last minute not to join press and top administration members on the jet leaving the NATO summit in Turkey.

Trump pretended to board the old Air Force One as planned -- only to secretly deplane from a different door, into a catering truck that took him to a third plane.

The move was in response to a reported security threat from Iran involving a surface-to-air missile.

Trump recently announced that work to enhance security measures on the new jet would begin in October and take two months -- a month longer than he had previously said.

The Qatari royal family donated the luxurious jet last year after Trump complained about the condition of the two older Air Force One aircraft, which feature a distinctive white, silver and robin`s egg blue color scheme and have been in service since 1990.

The donated plane, valued at several hundred million dollars, has raised major ethical and constitutional questions regarding gifts a US president may receive from foreign governments.

But it also raised questions about the security of military equipment given by a foreign power.

The jet has already been refitted by the military, and is to be used until Boeing delivers two new aircraft in the coming years.

Trump has indicated that he intends to keep the Qatari plane for his future presidential museum.