Sir Keir Starmer got a standing ovation as he condemned the “senseless” killings unleashed by Hamas “terrorists” in Israel in his speech to the Labour conference.

With war between Israel and the militants raging on for a fourth day, killing hundreds on both sides, the Labour leader was forced to tackle the developments head-on in his address in Liverpool.

He said he has been “shocked and appalled by events in Israel”, which was attacked by Hamas on Saturday, and was met with loud applause as he reiterated his support for Israel’s right to respond.

“I utterly condemn the senseless murder of men, women and children – including British citizens – in cold blood by the terrorists of Hamas,” Sir Keir said.

“This party believes in the two-state solution – a Palestinian state alongside a safe and secure Israel.

The world is becoming a more volatile place

“But this action by Hamas does nothing for Palestinians and Israel must always have the right to defend her people.

“And conference, these events, the war in Ukraine, they show precisely the test of our era. The world is becoming a more volatile place.”

Sir Keir’s words and the reception in the conference hall – with frontbenchers Yvette Cooper and David Lammy joining in the standing ovation – signals a shift from the era of Jeremy Corbyn’s leadership when Palestinian flags were waved in the arena.

Labour has been largely united in condemning Hamas’s wave of violence, while Mr Corbyn, who was attending events in Liverpool outside of the conference, resisted directly criticising the militant group.

Some on the left of the party have spoken up in support of the Palestinian people as Israel implements a full “siege” on more than two million people.

Shadow foreign secretary David Lammy called for humanitarian access to Gaza as he maintained support for a two-state solution between Israel and Palestine.

After days of lack of clarity over whether he would speak as planned at the Labour Friends of Palestine event on the fringes of the conference, Mr Lammy gave an address after it was confirmed Husam Zomlot – the head of the Palestinian mission in London – would no longer be appearing.

Mr Lammy condemned the “terrorist” attacks by Hamas, but said Israel’s response must be proportional and “in line with international law”.

“I agree with President Macron when he said we must not confuse the fight against terrorism, with the most elementary humanitarian support for civilian populations,” Mr Lammy said.

“There needs to be humanitarian access and supplies to Gaza. We must distinguish between Hamas and the Palestinian people because failure to do so would only embolden the terrorists and punish the wrong people.

“There will not be a just and lasting peace until Israel is secure, Palestine is a sovereign state and both Israelis and Palestinians enjoy security, dignity and human rights.”

He said it “may never have felt more distant than it does today” he would not give up hope for “two steps. living side by side in peace”.

Senior Labour MP John McDonnell urged supporters of the Palestinian people to “mobilise” to press for a ceasefire between Hamas and Israel to prevent a possible “annihilation of civilians” in Gaza.

Mr Corbyn’s former shadow chancellor told a Palestine Solidarity Campaign (PSC) event on the conference fringe that the Middle East may be set “alight” in a way never seen before without de-escalation.

Mr McDonnell, who has condemned Hamas for targeting civilians, told the meeting: “I think our role as individuals and members of the Labour and trade union movement, and every other organisation that we can possibly mobilise as well, is to try and get some acknowledgement that the key factor now must be the protection of civilians.

“I’m so fearful, I’m so worried that what’s happening in Gaza now is that we’re seeing almost an annihilation of civilians.

“And therefore everything we have to do now is to mobilise both within our own country, but internationally as well, to try and put pressure on the international community now to ensure that the attacks on Gaza end and that a form of dialogue is opened up to secure initially, at least some form of ceasefire, de-escalation, and then hopefully the first steps to a longer-term solution.

“I know we’ve been here so often before but I’m not sure we’ve been here on this scale of the potential loss of life – civilian loss of life in particular.

“If this continues on in this form, it could set the Middle East alight again on a scale we’ve not seen, maybe, ever.”

Shadow exports minister Afzal Khan apologised after posing for a photograph in front of a Palestinian flag saying “end apartheid now” at the PSC stall at the conference.

It can only be interpreted as an endorsement of an ongoing military occupation, support for human rights violations and as a green light for the Israeli government to proceed with intended war crimes

Mick Whelan, general secretary of the Aslef trade union, urged Labour supporters at the event to peacefully demonstrate in support of Palestinian people.

“If anybody in this room believes that this movement, this party, shouldn’t be on the side of everybody for a peaceful and just solution for self-determination, then we shouldn’t be in the Labour Party,” he said.

“I urge you to go out and call for the rights of self-determination for the Palestinian people, the most peaceful and best way possible, as quickly as possible.”

Ben Jamal, PSC director, criticised Prime Minister Rishi Sunak and London Mayor Sadiq Khan for having “emblazoned” public buildings with the Israeli flag, arguing the symbol should be extended to “all civilians who will have been killed in the past few days and will be killed in the coming weeks”.

“It can only be interpreted as an endorsement of an ongoing military occupation, support for human rights violations and as a green light for the Israeli government to proceed with intended war crimes,” he added.