Mr. Mueller crossed the US president's red line.

The confrontation between US President Donald Trump and Robert Mueller, the lead investigator into allegations of Russian interference in the US election, continues to escalate as Mueller expands his investigation into President Trump's business dealings.

Mr. Trump warned investigators not to interfere with his business dealings - Photo: Reuters

Bloomberg reported on July 21 that Mueller is scrutinizing Trump's deals to sell real estate to Russia, his collaboration with Russian associates in building hotels in downtown New York, and the 2013 Miss Universe pageant in Moscow...

This is the first time President Trump's business dealings have come under the scrutiny of an official investigation.

Earlier, in an interview with the New York Times, the US president drew a "red line" with Mueller, asserting that touching on his finances was "a violation." Trump even left open the possibility of firing Mueller.

There are reports that the special counsel is also investigating the business dealings of Trump's son-in-law, Jared Kushner.

Mueller was appointed to lead the special investigation on May 17th with extremely broad investigative powers. However, Trump's lawyers argue that Mueller has overstepped those limits this time.

Earlier, Trump and his team had stated they would closely monitor all actions of adviser Mueller.

However, Trump is not standing idly by either. The Washington Post reports that the president's lawyers are seeking to limit Mueller's investigation, which includes looking for conflicts of interest for Mueller or his team, such as ties to former FBI director James Comey, whom Trump fired earlier this year.

Additionally, they are considering the possibility, or whether Mr. Trump could, pardon himself in the investigation.

President Trump has been building a team of private lawyers outside the White House. Meanwhile, he also appointed former federal prosecutor Ty Cobb as White House special counsel last weekend.

According to TTO