Prince Albert of Monaco has expressed disappointment over the violent riots in the US Capitol and said President Donald Trump should be "held accountable" for spurring a revolt.

The reigning monarch of Monaco, who spent a part of his childhood in the US, said he was "shocked" into disbelief when he saw the violent riots at the U.S. Capitol on Wednesday, which has led to four deaths. A mob of Trump supporters had stormed the Capitol building when the lawmakers were certifying Joe Biden's win in the recent presidential elections. The breach came after the outgoing president addressed a crowd of his supporters at a rally near the White House encouraging them to go to the Congress and voice their anger "peacefully and patriotically."

Claiming that the Democrats are trying to "illegally take over" the country, Trump had said, "I know that everyone here will soon be marching over to the Capitol building." He had also warned his supporters, "if you don't fight like hell, you're not going to have a country anymore."

Speaking to People magazine about the siege, Prince Albert said: "This is not the America I know — the one I partially grew up in, went to school in. President Trump has to be held accountable."

The Monegasque royal, son of late American actress Grace Kelly, spoke about feeling sadness and anger after the tragic riots. The 62-year-old was partly raised in the US and also studied for four years at Amherst College in Massachusetts.

"I was up at our country house, Roc Agel, so as soon as I put on the news before going to bed, there it was — live from the streets of Washington. It's just unbelievable. I'm still in shock, but at the same time, I'm not totally surprised because, unfortunately, this is where we were heading," the monarch noted.

Prince Albert said that while his immediate reaction to the riots was "shock" and "disbelief," it quickly turned into "disgust."

"My immediate reaction was shock. My wife (Princess Charlene) had already retired and I told her afterward. It was shock and disbelief and then it kind of quickly turned into disgust, really. But also anger about how this could have happened and how this was fueled by President Trump," he said.

The head of the Princely House of Grimaldi added that Trump should be "held accountable" for the riots, noting that this is unprecedented in contemporary world history that a president who is still in office has directly and indirectly "spurred a revolt."

The royal had previously also been vocal about his dislike for Trump. Speaking to People last month when Trump was refusing to accept defeat in the presidential election, Albert had said: "This vast adhesion to these theories, this blind following of someone who is clearly not well, who is delusional. How we got to this point is what's troubling me."

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Princess Charlene of Monaco (L) and Prince Albert II of Monaco present the Prince Renier III Awards at the 2017 Princess Grace Awards Gala on October 25, 2017, in Beverly Hills, California Getty