Rudy Giuliani has accused Twitter of allowing someone to “invade” one of his tweets to spread an anti-Trump message, after the veteran Republican sent a message with a typo.

On 30 November, Giuliani sent a tweet criticising Robert Mueller for issuing an indictment just as Donald Trump was heading to the G20 summit in Buenos Aires. Giuliani said Mueller had done similar in July as Trump left for a meeting with Russian president Vladimir Putin, and that the actions could have been easily taken earlier or later. “Out of control! Supervision please?” declared the former mayor of New York’s tweet.

Facebook Twitter Pinterest Rudy Giuliani’s tweet, with the link to the G-20.In domain. Photograph: Twitter/Rudy Giuliani

Unfortunately for Giuliani, a lack of spacing between his sentences meant that Twitter automatically detected the phrase G-20.In as a potentially valid web URL operated from India, and turned it into a link. When publishing his tweet, Giuliani did not notice that Twitter had turned it blue, indicating it was clickable.

This was, however, spotted by Jason Velazquez, an Arizona-based website designer, who immediately saw the potential for a prank, and registered the domain. He then made G-2o.In into a real website – one with an anti-Trump message.

When Giuliani discovered this, he again used the social network, declaring that “Twitter allowed someone to invade my text with a disgusting anti-president message”.

Perhaps demonstrating a lack of understanding of how web hyperlinks work, he added: “The same thing – period no space – occurred later and it didn’t happen.”

Facebook Twitter Pinterest Rudy Giuliani’s tweet accusing Twitter of allowing someone to ‘invade’ his tweets. Photograph: Twitter/Rudy Giuliani

Echoing a common cry – sometimes made by Trump himself – that Silicon Valley’s digital giants are biased against Conservative voices, Giuliani suggested that Twitter had done this deliberately. “Don’t tell me they are not committed card-carrying anti-Trumpers,” he said, adding, while he was on the subject: “Time Magazine may also fit that description. He finished his tweet with an all-caps plea for “fairness please”.

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Velazquez’s webpage consists of two elements. It displayed the message that Giuliani described as “disgusting” – “Donald J Trump is a traitor to our country” – and carried a link to coverage of Mueller’s investigation.

Velazquez described setting up the site as 15 minutes’ work.

Facebook Twitter Pinterest The G-20.In website set up by Jason Velazquez to take advantage of Rudy Giuliani’s typo. Photograph: G-20.In/Jason Velazquez

A spokesperson for Twitter categorically denied Giuliani’s inference, stating “the accusation that we’re artificially injecting something into a tweet is completely false”.

Giuliani’s original tweet with the typo and the link to the anti-Trump website has been shared over 16,000 times since it was published. Giuliani has served as Trump’s lawyer, and also as his cybersecurity adviser.