THE age and service issues of a Ryanair Boeing jet have not been ruled out of a probe into an incident that saw a passenger sucked out a cabin window, investigators say.

The revelation comes just days after suggest “foreign object damage” caused the emergency.

Ryanair low cost airline in Eindhoven, NetherlandsThe age and service issues of the Boeing 737-800 has not been ruled out of the probe Credit: Getty : Ryanair's annual general meeting in DublinIt comes after Ryanair CEO Micheal O’Leary said finding suggest “foreign object damage” caused the incident Credit: Reuters

In a letter sent to O’Leary on Wednesday, the US National Transportation Safety Board (NTSB) said it “has not made any such determination.”

“Our investigators have not yet ruled out age or servicing issues as contributing to this event,” the letter added.

NTSB said O’Leary’s comments violated the agency’s rules on disclosure by parties to the investigation and urged him to refrain from commenting further.

The organisation is currently investigatingon board the 737-800 travelling from Thessaloniki, Greece, to Memmingen, Germany.

NINTCHDBPICT001095201460Ljubiša (left) was sucked out of a plane window while his wife Svetlana (right) clung onto his leg Credit: Facebook A broken window of the Ryanair aircraft, following a reported emergency landing, in location given as ThessalonikiThe smashed window yanked the unsuspecting passenger out up to his shoulders Credit: Reuters

Shortly after takeoff, a piece of the engine broke off the aircraft and smashed a window.

Passenger Ljubiša Karović, 61, was at 20,000ft while his wife, Svetlana, clung to his feet for five terrifying minutes.

The plane lost pressure, forcing the pilot to make an emergency landing.

Ljubiša was hospitalised with severe injuries after being sucked into the gap, exposing his head and neck to brutal 370mph winds.

The dad-of-two is now in a neck brace with burns on his back and right hand.

He was also temporarily paralysed – and his head had swollen while he suffered damage to his right ear and eye.

O’Leary said: “Initial indication would suggest it looks like a foreign object damage to the engine on takeoff at Thessaloniki, but we don’t have, we can’t say that definitively.”

He told analysts that despite the aircraft being 18 years old, its engine had been refurbished and fully serviced in the last two years.

The interior of the Ryanair aircraft, following a reported emergency landing, in location given as ThessalonikiThe plane lost pressure, forcing the pilot to make an emergency landing Credit: Reuters Illustration of a map detailing a Ryanair flight's emergency landing.

A draft report on the incident would be released within 28 days, followed by an in-depth report, he added.

If the damage was caused by an external object, it would reduce Boeing’s and ‘s responsibility for the incident.

Following the incident, the couple’s lawyer, Vasilis Tsiaras, told The Sun how they desperately tried to stuff luggage into the gap.

He said: “There was a big hole that they tried to seal with a suitcase, which was a little bit soft and was sucked from the plane.

“They tried to do the same with more of a tough suitcase and managed to stop the flow of the air.”

Tsiaras also claimed only the day before the incident.

The lawyer alleged the plane had been forced to return to Thessaloniki airport shortly after taking off for Sarajevo, Bosnia.

He said: “At this time we cannot claim that the two incidents are connected, however there is a strong suspicion that the problem is related to engine maintenance, as that is where it all seems to have started.”

The airline claimed that the incident was caused by a disruptive passenger, who had to be returned to the airport and removed.