Washington – Amazon founder and Washington Post owner Jeff Bezos fired back on Wednesday at Donald Trump, calling the presumptive Republican presidential nominee's barbs at him not "appropriate."Bezos, appearing at a Washington Post question-and-answer session, responded to a series of critical remarks by Trump, ranging from Amazon's taxes to the Post's reporting on the candidate.Bezos said it was proper for the newspaper to carry out its role of investigating presidential candidates."We want a society where any of us ... can scrutinise, examine and criticise an elected official, especially a candidate for president of the most powerful country on earth," Bezos said at the forum under questioning by Post executive editor Martin Baron."What would be shocking and disturbing if you were not doing that ... the Post has a long tradition of examining presidential candidates and there's no way that's going to change."Baron asked about comments made by Trump that Amazon was avoiding taxes, suggesting the online giant could have "problems" if he were elected and that Bezos had bought the Post as a tax dodge."My view is that's not an appropriate way for a presidential candidate to behave," Bezos said.Asked about the specifics of Amazon's business practices, he said, "I'm very, very comfortable with all of Amazon's approaches and behaviours."The comments came after a series of comments and tweetstorms by Trump targeting Bezos and Amazon starting last year.Trump had argued that the online retailer was not paying its fair share of taxes, that Bezos had bought the Post as a "tax shelter" and to keep politicians from raising taxes on Amazon.Bezos, who also owns the private space firm Blue Origin, tweeted in December that he would "still reserve him (Trump) a seat on the Blue Origin rocket."