When Prince Harry compared fighting in Afghanistan to playing a video game, the Taliban were quick to accuse him of mental illness and cowardice, joining a chorus of criticism from all sides.

But in Afghanistan's highest reaches of government he has found at least one ally.

President Hamid Karzai, usually quick to condemn western mis-steps in his country, told the Guardian that the young royal's comments may have been a mistake, but he should be let off the hook because of his age.

"Prince Harry is a young man, we do give exits to young men when they make mistakes," said Karzai, who is visiting the UK for a high-level conference, and also expects to meet Prince Charles before flying home.

A long-standing friendship with Charles, whom he described as a "great representative of Britain", may have contributed to Karzai's uncharacteristic reticence.

"Prince Charles, the father of Prince Harry, is a very fine gentleman, a man for whom I have tremendous respect," Karzai told the Guardian and ITV News in an exclusive interview, when asked whether he thought Harry had spoken unwisely.

But he also drew a telling contrast with Prince Charles's more peaceful reputation, as he reminisced about years of admiration for his friend's vocal advocacy of traditional building styles.

"For years, even when I was a student in Shimla, I used to read about his dislike of modern architecture and the cement buildings and I entirely agreed with him. Prince Charles is a great representative of Britain and the British ways of life," he said.

Karzai is visiting the UK for a trilateral meeting with the British prime minister, David Cameron, and the Pakistani president, Asif Ali Zardari, with the aim of improving fractious relations between the south Asian neighbours and ultimately pave the way for a peace deal with the Taliban.

He arrived shortly after the broadcast of several media interviews Harry gave to mark the end of a 20-week deployment as a co-pilot in an Apache attack helicopter stationed in Camp Bastion, in turbulent southern Helmand province.

Initially, much of the coverage of Harry, which included shots of him ripping out an earpiece as his aircraft was scrambled for an engagement, was greeted largely with admiration. But the description of his job as a "joy" sat uneasily with admissions that he had probably killed Taliban fighters from the helicopter.

"Take a life to save a life, that's what we revolve around. If there's people trying to do bad stuff to our guys, then we'll take them out of the game," he said. "I'm not here on a free pass … Our job out here is to make sure the guys are safe on the ground and if that means shooting someone who is shooting them, then we will do it."

The prince, who was in charge of firing the Apache's Hellfire air-to-surface missiles, rockets and 30mm gun, also said his taste for video games helped him in battle. "It's a joy for me because I'm one of those people who loves playing PlayStation and Xbox, so with my thumbs I like to think I'm probably quite useful," he said.

Pushed again about the remarks, Karzai said most people had made mistakes in their youth and shouldn't be hounded for that. "As I said, he's a young man, and young men do make mistakes talking, while behaving, all of us have gone through that period, so let's drop it there."

Harry's enemies on the battlefield, who have also said they are targeting Karzai even as his government tries to reach out to them, were not so reticent, describing the young prince as a coward who ran away from fighting the mujahideen, or "holy warriors", as the militants like to call themselves.

"I don't believe that he participated in the fighting," said Zabiullah Mujahid, a spokesman for the Taliban. "Maybe he has seen the mujahideen in a movie, but that's it."

He accused Harry, who has now completed two tours in one of Afghanistan's roughest provinces, of staying away from the fight. "I think he has a mental problem, that's why he is saying it is a game," he said. "These kind of people live like diplomats in Afghanistan, they can't risk themselves by standing against the mujahideen."

This article originally appeared on guardian.co.uk