In an op-ed posted to the newspaper's website, Bezos argued that with trust in news media falling, steps needed to be taken to address accusations of partisanship.

"What presidential endorsements actually do is create a perception of bias. A perception of non-independence. Ending them is a principled decision," he wrote.

The editorial board of the influential Post has endorsed candidates for much of the last four decades -- all of them Democrats -- before deciding to stay on the sidelines in one of the most polarizing elections in US history.

Republican Donald Trump is locked in a too-close-to-call race for the White House with Vice President Kamala Harris, with polls showing the two neck-and-neck in the seven swing states that will likely decide the election.

Bezos also rejected allegations that he had made the decision for personal gain, dismissing concerns regarding a meeting between the CEO of Blue Origin -- the billionaire's spacecraft company -- and Trump the day of the announcement.

"I would also like to be clear that no quid pro quo of any kind is at work here. Neither campaign nor candidate was consulted or informed at any level or in any way about this decision," he wrote. 

Bezos, who bought the Post for $250 million in 2013, has a slew of other companies, some of which have major contracts with the US government.

The Post's decision, announced on Friday, was met with criticism from many people, including its own subscribers.

On Monday, US media outlet NPR carried a report, citing two unnamed sources, that the Post had lost 200,000 digital subscribers since the announcement, representing eight percent of its total.

The Post's decision follows a similar move by the Los Angeles Times, another major US newspaper.