AG William Barr told Trump that Rudy Giuliani has become a liability, The Washington Post reports

Attorney General William Barr counseled President Donald Trump that his personal lawyer Rudy Giuliani has become a liability for his administration, The Washington Post reported Sunday, citing people familiar with the conversations.

In one instance, the Post said, Barr warned Trump that Giuliani was not serving him well as his lawyer, according to one person with knowledge of the situation.

Giuliani has long stirred alarm among the President's advisers who worry his foreign business dealings often make it unclear who he is representing, people familiar with the situation told the Post. The concerns, the newspaper said, have escalated since Giuliani emerged as a key player in the House impeachment inquiry into Trump's dealings with Ukraine.

CNN previously reported that investigators have been looking into Giuliani's business dealings in Ukraine and have dug into everything from possible financial entanglements with alleged corrupt Ukrainian figures to counterintelligence concerns raised by some of those business ties, according to people briefed on the matter.

The counterintelligence probe -- which indicates that FBI and criminal prosecutors in Manhattan are looking at a broader set of issues related to Giuliani -- hinges in part on whether a foreign influence operation was trying to take advantage of Giuliani's business ties in Ukraine and with wealthy foreigners to make inroads with the White House, according to one person briefed on the matter.

The Post and The New York Times also previously reported that Giuliani pursued hundreds of thousands of dollars in business from officials in Ukraine at the same time that he was using his connections there to unearth damaging information about former Vice President Joe Biden.

On Sunday, the Post reported on other foreign efforts by Giuliani, including an attempt to replace the ambassador to Qatar and an agreement to find a way to negotiate a back channel communication between Trump and Venezuelan President Nicolás Maduro .

The House impeachment inquiry is rooted in a whistleblower complaint that states in part that US officials were concerned about Giuliani and his contacts with Ukrainian officials. The whistleblower alleges that US officials believed Giuliani was a conduit for messages between the President and officials in Kiev and that he was at the helm of a problematic "circumvention of national security decision-making processes."

Giuliani has previously told CNN he has "no knowledge of any of that crap" in the whistleblower complaint.