Elon Musk countersued Twitter Inc on Friday, escalating his legal fight against the social media company over his bid to walk away from the $44 billion purchase, although the lawsuit was filed confidentially. Although the 164-page document was not publicly available, under court rules a redacted version could soon be made public.

Musk's lawsuit was filed hours after Chancellor Kathaleen McCormick of the Delaware Court of Chancery ordered a five-day trial beginning Oct. 17 to determine if Musk can walk away from the deal.

Musk, the world's richest person and chief executive of Tesla Inc, said he was abandoning the takeover and blamed Twitter Inc for breaching the agreement by misrepresenting the number of fake accounts on its platform.

Twitter sued days later, calling the fake account claims a distraction and saying Musk was bound by the merger contract to close the deal at $54.20 per share. The company's shares ended on Friday at $41.61, the highest close since Musk abandoned the deal.