The social network formerly known as Twitter has fully migrated over to X.com, owner Elon Musk said on Friday.

The billionaire head of Tesla, SpaceX and other companies, bought Twitter for $44 billion in late 2022 and announced the rebrand to X last July.

Although the logo and branding were changed to "X", the domain name remained Twitter.com until Friday.

"All core systems are now on X.com," Musk wrote on X, posting an image of a logo of a white X on a blue circle.

Queries to Twitter.com redirected users to X.com on Friday morning, though the original domain name still appeared on some browsers.

Musk has repeatedly used the letter X in the branding of his companies, starting in 1999 with his attempt to set up an online financial superstore called X.com.

When he bought Twitter, he set up a company called X Corp to close the deal.

Musk has said he wants "X" to become a super-app along the lines of China's WeChat.

The Chinese app is much bigger than X and weaves together messaging, voice and video calling, social media, mobile payment, games, news, online booking and other services.

He has also bolted onto X an AI chatbot called "Grok", which was launched in Europe this week.

Musk's leadership of X has proved controversial.

He has fired thousands of staff, overseen major technical problems and reinstated accounts of right-wing conspiracy theorists, as well as former US president Donald Trump.

European regulators have also begun probes into X and other social media platforms over fears of misinformation.

The EU demanded earlier this month that X explain its decision to cut content moderation staff, giving the firm a deadline of Friday.

AFP has contacted X for their response.

AFP