The law firm Mishcon de Reya has received racist and antisemitic abuse in response to handling a legal claim against Brexit.

Lord Pannick, QC, the barrister who has been instructed by Mischcon, told the Guardian that the firm had been threatened as a result of the case.

“The publicity that has accompanied notification of the legal issue has provoked a large quantity of abuse directed at my solicitors, Mishcon de Reya,” Lord Pannick said.

“It’s racist abuse, it’s antisemitic abuse and it’s objectionable. It’s contempt of court for people to make threats [with regard to ongoing legal proceedings]. It’s a very serious criminal matter.”

Mishcon declined to comment.

There are a number of law firms involved in the legal challenge to Brexit, but Mishcon is the most high-profile, having been highlighted by the Guido Fawkes political blog earlier this month.

Mishcon de Reya was formerly known as Victor Mishcon & co; it was established in 1937 and named after its founder, who was the Brixton-born son of a Russian Rabbi.