King Charles warned of much-awaited American guest's bombshell?

King Charles III is reportedly “very concerned” that his upcoming American guest could cause unexpected situation.

The monarch has been warned against reactions if the world's one of the most powerful men launched into an unfiltered rant about immigration while standing alongside him during his state visit to the United Kingdom in September.

There are speculations that the US president could upend protocol and make politicised comments when delivering a traditional speech at his state banquet. A civil servant also told the Daily Beast that there was a risk.

The palace was already concerned about Trump’s visit because of his comment about Canada, a British “realm” which counts the King as head of state, as the “51st state.”

But those concerns pale in comparison to the prospect of Trump using the official visit with the King as a platform to make further inflammatory remarks about immigration in the U.K.

On a visit to Scotland this week, President Donald Trump warned the United Kingdom that "this immigration is killing Europe."

Immigration has become a source of increasingly bitter division and public protest in the Britain in recent months after figures showed that record numbers of so-called “small boats” laden with undocumented immigrants have landed on British shores this year.

Hotels used to house migrants have seen violent protests flare, and Nigel Farage, the Reform U.K. leader credited with making Brexit happen, has warned that Britain is close to “civil disobedience on a vast scale” over the issue, according to a report.