Donald Trump flops over his pink and white baby walker and rolls it around his family's modest home in Kabul, blissfully unaware of the turmoil his "infidel" name is causing in Afghanistan.

The rosy-cheeked toddler's parents named him after the billionaire US president in the hope of replicating his success.

But now he is at the centre of a social media firestorm in Afghanistan after a photo of his ID papers was posted on Facebook.

Infidel name

A self-confessed fan of the American tycoon turned leader of US, Sayed Assadullah Pooya said he and his wife have been inundated with "vulgar and insulting" comments attacking their choice of name for their third child.

Some Facebook users have gone as far as threatening to kill Sayed for giving his son an "infidel name", while others have accused him of endangering the boy's life.

There are even suggestions Sayed is using the moniker to wangle asylum in the United States - a charge the 28-year-old teacher vehemently denies.

"I didn't know at the beginning that Afghan people would be so sensitive about a name," Sayed told AFP, as Donald played with a music app on his father's Samsung smartphone in their carpeted room.

Sayed says someone posted the picture online, sparking the controversy that forced him to close his Facebook account.

Even Sayed's neighbours in the heavily Shia area of Kabul where they live have threatened the family and told them to leave.

"When I go out of the house I feel intimidated," he said.

Inspired by Trump

Donald was born in the central province of Daikundi, a few months before the 2016 US presidential election, on the farm where Sayed's parents and grandparents grew almonds, wheat and corn.

Sayed was inspired to call his son Donald Trump after reading the Persian language versions of the businessman's books, including How to Get Rich, which he borrowed from the local library.

"I did a lot of research about him and that motivated me to choose his name for my son," he explained.

He hopes his son will "be as successful", adding that photos of the older Trump already make his younger namesake "happy".

But bemusement turned to anger when Sayed's parents realised the couple were serious about the name. As relations broke down the young family moved to Kabul, and they are now estranged from their relatives.

Their life could not be more different from the one enjoyed by their son's namesake, who divides his time between the White House and his Mar-a-Lago resort in Florida.

The family of five is squeezed into a spartan room overlooking a small courtyard and outdoor toilet, which they rent for 2,000 afghanis ($30) a month.

Not illegal

Despite the controversy, Donald's parents have not broken the law by giving their son a Western name, according to Rohullah Ahmadzai, a senior adviser at the Population Registration Office in Kabul.

He said they have the legal right "to name their children whatever they want" - even after American presidents.

While Sayed is worried about his family's safety, particularly Donald's, he remains stubbornly unrepentant.

"It's likely ... that he will be harassed or beaten by his classmates," he said matter of factly.

"I won't reconsider [his name]. To hell with the other people."