LONDON - A three-month-old British boy was summoned to the US embassy in London for questioning after his grandfather mistakenly listed him as a terrorist in a US form.

Harvey Kenyon-Cairns had been due to travel to Orlando, Florida, with his family for his first overseas holiday. While his grandfather Paul Kenyon was filing in the Electronic System for Travel Authorisation (Esta) form - required by the United States - for the baby, he mistakenly ticked "yes" in the section that reads: "Do you seek to engage in or have you ever engaged in terrorist activities, espionage, sabotage, or genocide?".

As a result, little Harvey's application was rejected, the Guardian reported.

And that's not all. The baby was summoned to the US embassy in London, to be questioned by officials, according to the report.

Kenyon, 62, and his daughter Faye brought Harvey from their home in Poynton, Cheshire, to the US embassy in London, just three days before their flight to the US.

"I couldn't believe that they couldn't see it was a genuine mistake and that a three-month-old baby would be no harm to anyone, " the Telegraph quoted Kenyon as saying.

"I went down with him and his mum and took him in for the interview, but he can't even speak as he's so young,'' he added.

Kenyon told the Guardian: "Baby Harvey was good as gold for the interview and never cried once... He's obviously never engaged in genocide, or espionage, but he has sabotaged quite a few nappies in his time, though I didn't tell them that at the US embassy."

The round trip from Poynton to London reportedly took about 10 hours, slightly longer than the 9.5-hour flight time from Manchester to Orlando.

Despite the trouble, the visa for baby Harvey failed to arrive in time. So his grandparents flew to Orlando on the scheduled date, while Harvey and his parents took the flight a few days later.

Kenyon said the mess-up cost him an extra £3,000 (S$5,254).

"It was a very expensive mistake, but I was hoping the US embassy would realise that it was just a simple error without us having to jump through all the hoops," the Guardian quoted Kenyon as saying.

"If you were a terrorist, I suspect you'd not be ticking yes on the Esta form anyway," he added.