The comments came a day after a report by the news site Axios that Trump was "obsessed" with Amazon
US President Donald Trump took aim Thursday at Amazon, claiming the US online giant pays too little in taxes and hurts other retailers.
"I have stated my concerns with Amazon long before the Election," Trump tweeted.
"Unlike others, they pay little or no taxes to state & local governments, use our Postal System as their Delivery Boy (causing tremendous loss to the U.S.), and are putting many thousands of retailers out of business!"
The comments came a day after a report by the news site Axios that Trump was "obsessed" with Amazon, believing the tech giant fails to pay enough taxes and gets preferential treatment from the US Postal Service.
The report said Trump's wealthy friends complain that Amazon is killing shopping malls and brick-and-mortar retailers.
Trump has long been at odds with Amazon founder Jeff Bezos, a vocal opponent of the Republican in the 2016 election campaign.
Bezos is also the owner of the Washington Post, a frequent target of Trump over its news coverage.
On Wednesday, a White House official declined to comment specifically on the report but commented that the president "has said he's always looking to create a level playing field for all businesses."
Longstanding tensionsDuring the 2016 campaign, Trump said the US online giant could have "a huge antitrust problem" if he were elected, and suggested Bezos bought the daily newspaper as a move to protect Amazon "so that they don't have to pay taxes and don't get sued for monopolistic tendencies."
Bezos responded by offering to send the Republican candidate to space with his Blue Origin space exploration firm. But after the election, the CEO offered congratulations, tweeting, "I for one give him my most open mind and wish him great success in his service to the country."
Amazon shares slumped more than four percent on Wednesday in the wake of the Axios report, and amid a broad decline in the tech sector over the firestorm following revelations of the hijacking of personal data on millions of Facebook users.
Other critics of Amazon have argued it has become too powerful, because of its dominance of online retail, which could be increased with its acquisition of the Whole Foods grocery chain.
The company has become a major player in cloud computing and streaming video, and has used its research in artificial intelligence to launch a popular line of devices powered by its digital assistant Alexa.
Amazon last year announced plans to open a second headquarters as a companion to its home in Seattle, Washington, setting off a frenzied competition by states and cities offering tax breaks to the tech giant.
The new Amazon "HQ2" could provide an estimated $5 billion in investments and 50,000 new jobs, according to the company