Prince Harry has said he warned Twitter’s boss Jack Dorsey about his platform allowing political unrest a day before the Capitol riot that led to five deaths.

The Duke of Sussex made the comments at the RE:WIRED tech forum in the US. He said: “I warned him his platform was allowing a coup to be staged. That email was sent the day before. And then it happened and I haven’t heard from him since.”

On the day of the 6 January riots, Donald Trump tweeted allegations of vote fraud before a rally in Washington DC. Members of the Proud Boy movement, a rightwing militia, stormed the Capitol to disrupt the official certification of Joe Biden’s victory in the White House race, as part of an attempt to overturn the election result.

Harry was speaking via video chat at a session discussing whether social media was contributing to misinformation and online hatred. Dorsey, who is Twitter’s chief executive, has so far not commented.

A study released in October by the social media analytics service Bot Sentinel identified 83 accounts on Twitter that it said were responsible for 70% of hateful content and misinformation aimed at Harry and his wife, Meghan.

Harry said that “perhaps the most disturbing part of this [study] was the number of British journalists who were interacting with them and amplifying the lies. But they regurgitate these lies as truth.”

He said social media companies were not doing enough to stop the spread of misinformation, and the internet was “being defined by hate, division and lies”.

He also argued that the word “Megxit”, used by the British press to describe the couple’s decision to quit their royal duties, was misogynistic.

Harry said the word was an example of online and media hatred. “Maybe people know this and maybe they don’t, but the term ‘Megxit’ was or is a misogynistic term, and it was created by a troll, amplified by royal correspondents, and it grew and grew and grew into mainstream media. But it began with a troll,” he said. He did not elaborate.

Harry and Meghan moved to California last year to lead a more independent life. He has said that part of the reason for their departure was the racist treatment of Meghan, whose mother is black and whose father is white, by the British tabloid media.