The 33-year-old midfielder admitted on his social media channels Monday that he had presented a forged certificate to avoid mandatory vaccination during the Covid crisis.

"At the time, I was very worried about the issue of Covid-19 vaccination... I felt deep mistrust regarding the vaccine and was gripped by anxiety and doubt," he said on Instagram.

"Today I clearly see that I made the wrong choice. It was a mistake. I am sorry," he wrote, adding that he was "cooperating fully with the relevant authorities".

The Lucerne public prosecutor's office is currently investigating the matter, according to Swiss media.

The Swiss Football Association meanwhile announced that it had decided, in agreement with the player, that he would not join the Swiss national team in Belek in Turkey for a training camp starting Monday.

"Following his personal statement regarding his vaccination status, Granit Xhaka will not participate in the men's national team's upcoming gathering," it said in a statement.

"We welcome the fact that Granit is taking this step and is prepared to fully clarify the situation," Swiss FA president Peter Knabel said in the statement.

"At the same time, we mutually concluded that it was in the team's best interest to proceed with this gathering without him," he said.

"Our priority now is to calm the situation and focus entirely on the team and the upcoming UEFA Nations League fixtures."

Switzerland begin their campaign away to North Macedonia on Saturday and then travel to face Scotland on September 29th.

On October 3rd and 6th, the Swiss will host Slovenia and North Macedonia in Lucerne.

"At the end of this international window we will reassess the situation with Granit and discuss the next steps," Knabel said.

Switzerland are subsequently set to face Slovenia on November 13th and Scotland on November 16th, also as part of the Nations League.