A group of politicians, writers and activists including Baroness Jenny Tonge, Labour MP Sir Gerald Kaufman and playwright Caryl Churchill have sent a letter calling for the government to drop its planned change to the law on universal jurisdiction.

The letter, published in the Guardian newspaper today, was signed by more than 50 people including 21 MPs.

The group opposes legislation contained within the Police Reform and Social Responsibility bill which would require the Director of Public Prosecutions to sign off any arrest warrants for visiting foreign dignitaries.

As it stands, the law allows magistrates to grant warrants. A pro-Palestinian group used it last December, forcing Israeli opposition leader Tzipi Livni to cancel a planned speech in London.

Signatories of the letter, which argues that the reform “would risk creating a culture of impunity” include former MP Martin Linton, who last April spoke of the “long tentacles of Israel" reaching into British politics, and Labour MP Jeremy Corbyn, who last month was censured by press watchdog Ofcom for breaching standards on impartiality during a programme on Israel.

Support also comes from Liberal Democrat MP Mike Hancock, whose former parliamentary aide is under investigation for spring for Russia, and from trade union leader Bob Crow.

Filmmaker Ken Loach, who has previously backed a boycott of Israel, is on the list, as is the chairman of the Friends of Al Aqsa group, Ismail Patel, who once saluted Hamas for "standing up to Israel".

The letter, whose signatories include members of the Palestine Solidarity Campaign, the Campaign for Nuclear Disarmament, and Jews for Justice for Palestinians, argues the change would risk political interference by ministers in these cases and could allow people suspected of war crimes to escape justice.

They said: “[it] would constitute a gross interference with the rights of the victim and the responsibilities of the judiciary”.

Today's letter follows one sent to the same newspaper last week, signed by Michael Mansfield QC, which argued that there was no proof that arrest warrants were "handed out on the basis of "flimsy evidence".”

More than 100 MPs have also backed an Early Day Motion opposing the change, proposed by Mr Corbyn. The motion said: “universal jurisdiction for human rights abuses is essential as part of the cause of bringing to justice those who commit crimes against humanity.”