A Scottish Conservative MP has fallen for a “blindingly obvious” TV hoax about an ethical drug-dealing app.

Ross Thomson was pranked by a new comedy show which invented a spoof app called “Instantgrammes” that claimed to educate the children making its cocaine in Colombia.

The Ministry of Justice on Channel 4 showed the MP a fake advert in which a nine-year-old boy claimed to working for a drugs cartel in association with Instantgrammes.

He said the drug-dealing app was helping him get through school and become a dentist.

“It’s half school, half drugs plantation,” the boy said. “Best of all, it’s fairtrade!”

Mr Thomson, who recently claimed on BBC Question that it was quicker to use an online app to order cocaine in Glasgow than pizza, did not endorse Instantgrammes, but said it made ordering drugs online “sound cool”.

After the hoax was exposed, he complained the show had acted in an “underhand” way.

The SNP said he had shown “poor judgment” in the face of a “blindingly obvious prank”.

Former Tory party leader Iain Duncan Smith was also taken in by the fake app.

The fake advert shown to Mr Thomson ended with a warning that trespassers to the boy's school would be “shot on sight”, but there were “open evenings last Thursday of each month”.

In his instant reaction to it, Mr Thomson said: “It’s really worrying that we see these kind of promotional videos . It shows that the government needs to take more action in schools.

“Watching that video just made my skin crawl about how you see these young kids in Colombia being exploited to say that, somehow, actually, drugs is making my life a lot better.

“Of course it’s not. These kids were probably made to do that.

“Are we getting to a point now where people now think drugs are cool because you’ve got videos like this? You’ve got apps. And let’s be honest, some of my favourite TV series involve drugs. Breaking Bad - love Breaking Bad.”

He added: “The development of apps like Instantgrammes, which can easily downloaded on to your phone or tablet to order drugs, it makes it look cool.

“I know that sounds ridiculous, but it makes it look cool.”

Mr Thomson, a former MSP who was elected to Westminster last year, has a history of gaffes, including posing for jokey photos on a parliamentary fact-finding trip to Iraq.

He posted a smiling photograph of himself sitting in the throne of former ruler Saddam Hussein and said he was channelling his “inner dictator”.

Kirsty Blackman, the SNP MP for Aberdeen North, said: “This is an astonishing display of poor judgement, even by Ross Thomson’s standards.

“I take the issues of drug abuse and addiction incredibly seriously and it is vital that MPs educate themselves on facts presented by reputable organisations.

“The fact Ross Thomson fell for this blindingly obvious prank might go some way to explain his ill-informed claims over drugs made during a recent Question Time appearance.

“I think people across the north-east will be taken aback to witness an MP being so gullible.”

Mr Thomson said: “These people presented themselves as a legitimate production company.

“Along with other parliamentary colleagues, I took what they said at face value.

“I think this is a pretty underhanded way to approach a very serious issue.”