Billionaire Elon Musk has slammed the markets regulator Securities and Exchange Commission (SEC) over probes into Neuralink – a neurotechnology firm owned by the world’s richest man – and the purchase of Twitter shares.

His lawyer Alex Spiro has asked Gary Clenser, chief of the SEC, has flagged “more than six years of harassment” by the Commission and its staff, and demanded to known who had directed these actions – him or the White House.

“These tactics and misguided scheme will not intimidate us. We reserve all rights,” the lawyer said in a letter to Clenser.

The letter said Musk has been served a settlement demand by the SEC, asking him to accept a monetary payment or face charges on numerous counts. It, however, did not mention what the charges may be and how they impact companies owned by Elon Musk.