Ken Livingstone suggested Labour will have to lift his suspension over controversial remarks linking Adolf Hitler to Zionism as the row over the party's handling of anti-Semitism allegations continued.

The former London mayor was suspended over comments branded "vile, offensive and crass" by the party's deputy leader, Tom Watson, who said Mr Livingstone had "let down the Labour Party".

Read more: Livingstone: Corbyn ally- and friend

But Mr Livingstone, who faces calls to be expelled over his remarks, claimed that the party's internal inquiry would have to let him back in because "it's hard for somebody to decide to suspend me from the party" when he had been making the same point for 30 years.

The former MP, an ally of party leader Jeremy Corbyn, sparked fury among colleagues by claiming that Hitler had supported Zionism "before he went mad and ended up killing six million Jews".

Mr Livingstone was unrepentant despite his suspension, saying: "How can the truth be an offence? If I had lied that would be offensive."

He told Sky News his defence would rest on a book by controversial American Marxist historian Lenni Brenner - whom he met in the 1980s when he was leader of the Greater London Council - alleging collusion between the Nazis and early campaigners for a Jewish homeland.

Read more: Corbyn hits out at critics as he suspends Livingstone over 'Nazi apologist' accusation

"I'll just produce the evidence and I mean it's hard for somebody to decide to suspend me from the party here when all this was there 30 years ago in the public domain and nobody raised a peep," he said.

In a swipe at his critics, he added: "I suspect most of the pro-Israel Labour MPs have no idea about the history, they certainly don't teach about 1930s Zionist policy in Israeli schools ... almost everyone in the Jewish community grows up in complete ignorance of this."

Labour has faced criticism from inside and outside the party over its response to allegations of anti-Semitism and Mr Watson indicated that rules and procedures could be changed to ensure it has a "zero-tolerance" approach.

Asked if he thought Mr Livingstone's comments were anti-Semitic, Mr Watson said: "I personally think that Ken Livingstone was straying into that territory.

"But they were certainly offensive and provocative.

"To link Hitler and Zionism in the way he did must have been done to create offence."

It was now for the party's National Executive Committee to decide whether to expel Mr Livingstone from the party, Mr Watson told BBC Radio 4's Today programme.

"But no-one is in any doubt that Ken Livingstone's behaviour yesterday has let down the Labour Party, let down those thousands of candidates who are standing in an election next Thursday and caused deep offence, in particular to the Jewish community in Britain but also to people out there who expect the Labour Party to adhere to higher standards.

"And our National Executive Committee will deal with that."

Mr Corbyn has insisted there is not a "crisis" within the Labour Party but his handling of anti-Semitism allegations, which have also led to the suspension of Bradford West MP Naz Shah, has been criticised.

In a sign that Labour is attempting to demonstrate action on the issue, Mr Watson said he and Mr Corbyn had "both been talking to representatives of the Jewish community to look at whether Labour's own structures can be improved to make sure that we send a very clear signal to people in our party that we will have a zero-tolerance approach to anti-Semitism".

The could mean looking at potential candidates and "there are issues like are our rules robust enough and our procedures".

The president of the Board of Deputies of British Jews called for Mr Corbyn to acknowledge that past meetings with anti-Semites were "inappropriate" and condemned Mr Livingstone.

Jonathan Arkush told Today: "It was much more than offensive language. Ken Livingstone actually said that Hitler was some sort of Zionist.

"What Ken Livingstone deliberately did was to draw an equation between Nazism and Zionism.

"He therefore crossed a line into certainly what most people would regard as distinctly anti-Semitic."

Urging Mr Corbyn to get a grip on the problem, he highlighted the Labour leader's past praise for his "friends" in Hamas and Hezbollah and said: "I also want Jeremy Corbyn finally to say that his own meetings with anti-Semites in the past, before he became leader, were inappropriate and should not be repeated."

The leader of Israel's Labour party said the string of events were a "red alert" and called for action to be taken.

Isaac Herzog told BBC Radio 4's The World at One: "It's a red alert that comes from within the body politic of the British Labour Party.

"It doesn't symbolise the majority of the British Labour Party. However, this collection of recent events in a short time span show it has to be treated and I would focus not only on the political side but also on educating, explaining the issues at stake before people say such horrific things."