Elon Musk’s lawyers are fighting efforts by lawyers for investors suing Tesla to bring his girlfriend into the case.

In court filings published on Thursday, Musk’s lawyer Dean Kristy said lawyers suing the company were “sensationalising” the case by trying to collect evidence from his then-girlfriend, a Canadian musician known as Grimes.

Lawyers for plaintiffs in the case argued that Grimes, whose real name is Claire Elise Boucher, would have relevant information about the tweet, sent on August 7 last year, because she spent the day with him.

Investors sued Tesla and Mr Musk after he tweeted a claim that he had secured funding to take Tesla private at $420 a share. A separate lawsuit brought by the Securities and Exchange Commission, which said the statement was misleading, was settled for a total of $40m last September.

Lawyers for investors in this case said both she and her “current or former” friend, US rapper Azealia Banks, were “in direct contact with Musk in the hours and days following the tweet” and might have evidence which was in danger of being destroyed because it was likely to be stored electronically, such as on social media.

But Mr Kristy said this was “rank speculation”, and that there was no evidence that either one had relevant information.