UK Labour leader Keir Starmer condemned an attack on Israel by the Palestinian group Hamas, saying it must be “called out across the world.”

“This is an appalling attack on Israel, a terrorist attack, for which there is no justification,” he told BBC’s Sunday with Laura Kuenssberg. “The perpetrators of this have deliberately pushed back the prospect of peace agreements.”

Starmer’s clear condemnation of Hamas is in stark contrast to his predecessor Jeremy Corbyn, who before becoming Labour leader had a history of sharing platforms with supporters of both Hamas and Hezbollah. Starmer ejected Corbyn from the parliamentary Labour Party for failing to accept the results of a report into antisemitism in the opposition during his stewardship from 2015-2020.

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Corbyn called for an “immediate ceasefire and an urgent de-escalation” to the fighting in a post on X, formerly known as Twitter, on Saturday. But he faced criticism for failing to condemn Hamas.

While currently not a Labour MP, Corbyn remains a party member and he and his allies could cause a headache for Starmer at Labour’s high-profile annual conference in Liverpool, northwest England this week.

Corbyn, who has been criticized for sharing platforms with a range of extremists over the years, is expected to speak at the left-wing “World Transformed” festival in Liverpool in the coming days.

The UK previously distinguished between Hamas’s military and political wings, only proscribing the former. But in November 2021, the government banned it in its entirety, saying “Hamas is a complex but single terrorist organization.”