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"Labour utterly condemns Hamas's appalling attack on Israel,” said Mr Lammy.
"There is never a justification for terrorism. Labour stands firmly in support of Israel's right to defend itself, rescue hostages and protect its citizens.
"The hostages so cruelly taken, including children, should be released immediately and Hamas's indiscriminate attacks set back the cause of peace – both Israelis and Palestinians paying a terrible price.
"Though it may never have felt more distant, we will not surrender the hope of two states living side-by-side in peace."
He is the latest leading figure of the party to speak out about the escalating Gaza conflict during the conference, which runs until Wednesday.
“It’s an appalling act of terrorism, it needs to be called out across the world,” Mr Starmer said.
“Israel has the right to defend itself.”
Wes Streeting, Labour’s shadow health secretary, shed light on the widespread violence that has been broadcast globally.
He said the violence “has to be unequivocally condemned”.
Mr Streeting expressed solidarity with Israel's right to self-defence, noting the detrimental effect of the continuing conflict on hopes for a peaceful resolution.
Former leader Jeremy Corbyn emphasised the need for an immediate ceasefire.
“The unfolding events in Israel and Palestine are deeply alarming,” Mr Corbyn said, stating that an end the occupation is the only viable path towards sustained peace.