Israeli Prime Minister Benjamin Netanyahu and British opposition leader Jeremy Corbyn were locked in a row Tuesday over the Labour MP's attendance of an event that honoured suspects of the Munich Olympics massacre.

Corbyn has been accused of joining in a ceremony which included tributes to members of Black September, the group responsible for the killing of 11 Israeli athletes and coaches at the 1972 Olympic Games in Munich.

Netanyahu tweeted Monday that "the laying of a wreath by Jeremy Corbyn on the graves of the terrorist who perpetrated the Munich massacre... deserves unequivocal condemnation from everyone – left, right and everything in between."

Corbyn tweeted back that the Israeli premier's "claims about my actions and words are false", saying earlier that he "didn't think" he was involved in the wreath-laying.

"What deserves unequivocal condemnation is the killing of over 160 Palestinian protesters in Gaza by Israeli forces since March, including dozens of children," he added.

The British leader admitted recently that his party had a "real problem" with antisemitism following a string of accusations against members of his party.

The latest scandal erupted after a picture emerged of Corbyn, a veteran pro-Palestinian campaigner, holding a wreath at the Cemetery of the Martyrs of Palestine, Tunisia, in 2014.

Atef Bseiso, who is buried at the site, was regarded as one of the ringleaders. He was shot dead in Paris in 1992, believed executed by Israeli intelligence agency Mossad.

Corbyn initially said he was commemorating 47 Palestinians killed during an Israeli bombing raid in Tunisia in 1985.

But images recovered from a Palestinian Embassy archive show him holding a wreath in front of a plaque dedicated to members of Black September.

"A wreath was indeed laid by some of those who were at the conference to those that were killed in Paris in 1992," he said on Monday.

"I was present at that wreath-laying, I don't think I was actually involved in it," he added.

The event initially came to light in the run-up to last year's general election, but re-emerged after the Daily Mail uncovered the photographs this week.