Donald Trump, widely known for playing a successful businessman on TV, has some pointed business advice for Amazon: beware the regulator. Now the presumptive nominee to become the Republican party's presidential candidate in this year's election, Trump believes Amazon has "a huge antitrust problem" and "is getting away with murder, tax-wise."

His remarks were made in a Fox News interview with Sean Hannity last night, prompted by the host's query about the Jeff Bezos-owned Washington Post and its close scrutiny of Trump's affairs. Bezos is the founder and CEO of Amazon, and has already been the subject of Trump's wrath. Back in February, the Republican presidential candidate claimed the Washington Post was being used as an implement of lobbying and improper influence by Bezos. In a rally in Fort Worth, Texas, Trump said he would "open up our libel laws so when they write purposely negative and horrible and false articles, we can sue them and wins lots of money."

Today's line of attack is not about the Post's editorial direction or content, but rather about Amazon's incredible reach and influence within the US retail sector. While Trump doesn't elaborate on what part of Amazon's business he believes is in breach of antitrust rules, European investigators and independent US bookstores have identified its tight control of the ebooks market as problematic. In any case, Trump's overarching message is that, under his presidency, Jeff Bezos and Amazon would face tougher oversight from the government — which runs counter to the traditional Republican talking points about less regulation and governmental interference.