Donald Trump has renewed his attacks on the world’s richest man and his arch nemesis, Jeff Bezos, railing against the Bezos-owned Washington Post and Amazon, the original source of the entrepreneur’s $150bn fortune.

In an early morning flurry, Trump ripped into “The Amazon Washington Post” after the paper reported that the US president is frustrated with North Korea nuclear disarmament talks that have reportedly become bogged down by intransigence on the part of its leader Kim Jong-un’s negotiators.

Trump claimed the newspaper had “gone crazy” against him since Amazon “lost the Internet Tax Case in the U.S. Supreme Court”, and soon after adding: “....In my opinion the Washington Post is nothing more than an expensive (the paper loses a fortune) lobbyist for Amazon. Is it used as protection against antitrust claims which many feel should be brought?”

Trump was referring to a supreme court ruling in June that confirmed the right of states to collect sales tax from online sales, a move designed to level the playing field with brick-and-mortar retail and smaller online rivals.

Trump has frequently criticized Amazon and called for the levy of greater taxes on its sales. Amazon says it already collects sales tax in every state on the products it sells directly.

But on Monday Trump repeated his criticism of Amazon’s deal with the US Postal Service that he claims is unfairly weighted in Amazon’s favor.

“Next up is the U.S. Post Office which they use, at a fraction of real cost, as their ‘delivery boy’ for a BIG percentage of their packages....”

After an escalation of attacks on Amazon in April, Trump issued an executive order to establish a taskforce to evaluate the operations and finances of the postal service.

Trump routinely describes Bezos’s publication as “The Fake News Washington Post” and Amazon’s “chief lobbyist”. In April he ranted to reporters on Air Force One: “Amazon is just not on an even playing field. They have a tremendous lobbying effort, in addition to having the Washington Post … What they have is a very uneven playing field.”

After Trump’s initial attacks Amazon stock dropped from a $1,600 high on 12 March to $1,443 a month later – a $73bn drop in market capitalization over the past month. That fall caused Bezos’s fortune to decline around $16bn.

But in the three months since, Amazon’s stock has soared to $1,805, boosting Bezos’s fortune – which he says he intends to spend on space exploration – to $150bn, making him comfortably the world’s richest man.

On Monday, Amazon’s stock dropped 2% in trading after Trump’s latest tweets, before recovering.