Labour leader Ed Miliband said David Cameron's "silence" on events in Gaza is "inexplicable".
Miliband criticised Israel's military offensive as "wrong and unjustifiable" and called on the government to produce a clear and united message on the crisis.
The Prime Minister is wrong not to have opposed Israel's incursion into Gaza.
His silence on the killing of hundreds of innocent Palestinian civilians caused by Israel's military action will be inexplicable to people across Britain and internationally.
We need the clear and unequivocal message that has not so far been provided to be sent from Britain to both sides in this conflict.
David Cameron and the Cabinet must put Britain in a leading role in pressuring both sides now to end the violence.
More top news
A 20-year-old man who died in a triple stabbing outside Parsons Green Tube station has been named by police.
Capable of crossing the Atlantic in under three hours, Concorde flew at over twice the speed of sound, reaching altitudes of 60,000ft.
The announcement is part of a £500 million cost-cutting drive which will take place over three years.