The Prime Minister Gordon Brown has condemned the Israeli shelling of the United Nations HQ in Gaza as "indefensible".
The UN building was set alight by the bombardment as its secretary general Ban Ki-moon visited the area on a mission to secure a ceasefire.
Mr Brown, speaking on his return from Berlin and Paris, where he had discussed the crisis, said: "Today's attack on the UN headquarters in Gaza is indefensible.
"The UN's mission in Gaza is purely humanitarian, bringing relief to civilians suffering in appalling conditions as a result of the ongoing military action and restrictions on food and medical supplies entering Gaza.
"UN staff are working on behalf of the international community - any attack on them is unacceptable, as Israel has acknowledged.
"The intensification of Israeli military action, and continued Hamas rocket attacks, reinforce the urgency of our call for an immediate ceasefire.
"I will speak this afternoon to the UN's secretary general and to regional leaders, to underline the UK's unwavering support for the UN's efforts to secure a ceasefire."
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here