A football club has apologised after it published images of a new clothing line with “United 93” printed on the back – the call sign of one of the aircraft hijacked on 9/11.

The clothing was supposed to make reference to Oxford United’s founding year of 1893.

However, it said it had been released “without understanding of the historical context and associations”.

United Airlines Flight 93 crashed in Shanksville, Pennsylvania, killing all 44 people on board after being hijacked on 11 September 2001. A docudrama film titled United 93 was made about the tragedy and released in 2006.

Oxford United was founded in 1893 as an amateur club called Headington and now plays in League One – the third tier of the English football pyramid.

In a statement, the club said its Campus Clothing range had been withdrawn and it “sincerely apologised” for the error.

“It should not have reached the point of sale and we take full responsibility for not undertaking proper due diligence,” it said.

“We have removed the collection with immediate effect and are reviewing our approval processes to ensure nothing like this happens again.”

The 9/11 attacks saw 19 Al Qaeda members hijack four commercial passenger planes in the US.

Two of them were flown into the Twin Towers of the World Trade Center in New York City, resulting in them both collapsing.

Another plane struck the Pentagon, near Washington DC, while the fourth plane – United 93 – crashed in rural Pennsylvania. It was believed to be destined for the US Capitol Building, also in Washington DC.

The attacks killed 2,977 people and injured tens of thousands more.