Elon Musk on Tuesday offered to push through with his buyout of Twitter at the original agreed price, just weeks before the scheduled start of a bitter court case over his efforts to withdraw from the deal.

The world's richest man said in a filing with the US Securities and Exchange Commission that he sent Twitter a letter vowing to honour the contract.

The latest twist in the long-running saga came ahead of the high-stakes trial instigated by Twitter in an attempt to hold the Tesla chief to the deal he signed in April.

Musk's potential stewardship of the social media site has sparked worry from activists who fear he could open the gates to more abusive and misinformative posts.

Early reports on Tuesday of the U-turn by Musk prompted a surge in Twitter's share value that triggered a suspension of trading, which resumed after the regulatory filing.

"We write to notify you that the Musk Parties intend to proceed to closing of the transaction," read a copy of the letter to Twitter filed with the SEC.

Twitter confirmed that it received the letter from Musk, and said it intends to close the buyout deal at the agreed-on price of US$54.20 per share.

Conditions noted in Musk's letter included that the court halt action in the lawsuit against him. He had been slated to be questioned under oath by Twitter attorneys later this week.

"I think that Musk realised he was not going to win that trial," said University of Richmond law professor Carl Tobias.

"Ever since he had buyer's remorse, the problem has been why, and why had he not done due diligence up front."

A serial entrepreneur made rich through his success with Tesla electric cars, Musk began to step back from the Twitter deal soon after it was agreed.

He said in July that he was cancelling the purchase because he was misled by Twitter concerning the number of fake "bot" accounts, allegations rejected by the company.

Twitter, meanwhile, has sought to prove Musk was contriving excuses to walk away because he changed his mind.

In July, a Delaware judge agreed to fast-track a trial on Twitter's allegations, which the company argued is impeding its financial performance.

Wedbush analyst Dan Ives said in an email that Musk's apparent pivot showed that he recognised "this US$44 billion deal was going to be completed one way or another." (AFP)