British Prime Minister David Cameron has pledged to look into a recent case where a British Muslim family was barred by the US authorities from boarding a flight to Los Angeles at London's Gatwick Airport.

The family of 11, who had been saving for months for their dream holiday, had already obtained the requisite travel authorisation weeks ahead of their flight on Dec 15, The Guardian reported.

They had planned to visit relatives in Southern California and were looking forward to go to Disneyland and Universal Studios.

But their hopes were dashed after US homeland security officers approached them while they were in a queue at the departure lounge in Gatwick, saying that their authorisation to travel had been cancelled. No explanation was provided.

Mr Mohammad Tariq Mahmood, who spoke to The Guardian, claimed that the reason was obvious. "It's because of the attacks on America. They think every Muslim poses a threat," he said.

Mr Tariq and his brother, along with their nine children aged between eight and 19, were also made to return the items they had bought from the airport's duty-free shops before being escorted out.

"I have never been more embarrassed in my life. I work here, I have a business here. But we were alienated," Mr Tariq said, adding that he and his brother had never been in trouble with the police.

The £9,000 (S$18,741) they paid for their air tickets were also not refunded.

The treatment of Mr Tariq and his family has sparked wider concerns of a growing discrimination against British Muslims from the US authorities.

This is believed to have been exacerbated by US Republican presidential candidate Donald Trump's recent comments calling for a blanket ban on all Muslims entering the country, in the wake of the Nov 13 Paris terror attacks and the Dec 2 mass shooting in San Bernardino, California.

The plight of Mr Tariq and his family was raised by British Labour MP Stella Creasy, who wrote to Mr Cameron expressing her concern that more British Muslims have been refused entry into the US without being told why.

Ms Creasy added that she had "hit a brick wall" in trying to obtain answers from the American Embassy.

A spokesman for Mr Cameron said: "We are looking into the issue and the Prime Minister will respond in due course."

The US Customs and Border Protection agency said in a statement issued in London: "The religion, faith, or spiritual beliefs of an international traveller are not determining factors about his/her admissibility into the US."

It added: "... applicants for admission bear the burden of proof to establish that they are clearly eligible to enter the United States.

"In order to demonstrate that they are admissible, the applicant must overcome all grounds of inadmissibility."

A similar experience also befell another British Muslim. Bristol-based lecturer Ajmal Mansoor was turned away while attempting to board a flight to New York.

In a Facebook post on Dec 18, he wrote: "I am baffled, annoyed and angry at the moment. USA has the right to issue and revoke visa - I fully understand that. However not forwarding any reasons infuriates ordinary people."