Joss MacDonald (pictured), a Labour Party speech writer, has also branded Israel an ‘apartheid’ state and insisted people excuse its behaviour ‘because of the Holocaust’

Labour was plunged into a new ‘anti-Semitism’ row last night over claims by a key aide of leader Jeremy Corbyn that Israel was guilty of ‘genocide’.

Joss MacDonald, a Labour Party speech writer, has also branded Israel an ‘apartheid’ state and insisted people excuse its behaviour ‘because of the Holocaust’.

Last night, Mr Corbyn faced calls to sack Mr MacDonald for his ‘anti-Semitic’ language.

The row erupted just days after Labour confirmed that former London mayor Ken Livingstone was suspended indefinitely from the party over his claim that Nazi leader Adolf Hitler supported Zionism before he went ‘mad’. It also comes with the party still in turmoil over receiving £540,000 of ‘racially tainted’ money from tycoon Max Mosley after it emerged a 1961 leaflet linked ‘coloured’ immigrants with disease was published in the privacy campaigner’s name.

Allies of Labour deputy leader Tom Watson – who received the Mosley cash – yesterday claimed he had been ‘bounced’ into agreeing to take no more money from the former F1 boss. Mr Corbyn’s office denied the claim.

Boasting he is a ‘permanent Red’, MacDonald holds a Commons pass courtesy of the Labour leader. In September 2014, in the aftermath of the Israel/Gaza conflict, he was drawn into a row over who was to blame with another Twitter user. He wrote: ‘Sounds like an admission that Israel is committing genocide and that you’re excusing it because of the Holocaust.’

Four years earlier, Mr MacDonald wrote: ‘Apartheid Israel has killed the two-state solution: the only future is a bi-national democratic Palestine.’

The row erupted just days after Labour confirmed that former London mayor Ken Livingstone (pictured) was suspended indefinitely from the party following comments about Hitler

The remarks will revive many Labour MPs’ concerns that Mr Corbyn’s office is institutionally biased against Israel and in favour of the Palestinians.The Labour leader himself famously once described members of Hamas and Hezbollah as ‘friends’ though he later said he regretted the remark.Last night, Tory MP Andrew Percy called on Mr Corbyn to take action against Mr MacDonald.

Mr Percy, who is Jewish, said: ‘Accusing Israel of a genocide is a disgusting slur and Jeremy Corbyn should reconsider his decision to employ this man.’ Jeremy Corbyn promised a “kinder politics” but he continues to turn a blind eye to people around him who do and say things which are unacceptable in public life. These tweets show yet again that Labour have a systematic problem with anti-Semitic racism which needs to be addressed urgently.’

Labour sources last night defended Mr MacDonald, saying he was being critical of Israel not anti-semitic.