Twitter says it is investigating after a number of high-profile accounts were apparently hacked.
Accounts including those of former US president Barack Obama, presidential hopeful Joe Biden and billionaire Elon Musk all had messages about Bitcoin posted on them.
Businessman Mike Bloomberg, Amazon chief Jeff Bezos and Microsoft co-founder Bill Gates were also among those affected.
The fake tweets, which were quickly deleted, offered to send $ 2,000 for every $ 1,000 sent to a bitcoin address.
Twitter said in a statement: “We are aware of a security incident impacting accounts on Twitter.
“We are investigating and taking steps to fix it. We will update everyone shortly.”