Israel’s armed forces have distributed an image of the Houses of Parliament in London under missile attack, in the hope of persuading Britons that the country’s military incursion into Gaza is justified.

UN secretary-general Ban Ki-Moon and US secretary of state John Kerry were heading to Cairo to support an Egyptian initiative to end two weeks of fighting between Israel and Hamas terrorists that has killed at least 510 Palestinians and 20 Israelis and driven tens of thousands of Gaza residents from their homes.

10354881_815035548519317_6721625812328746216_nIsraeli defence minister Moshe Yaalon has said he is prepared to continue the offensive “as long as necessary” to halt rocket fire and other attacks from Gaza, which Israel blames on the Hamas government which controls the enclave. Since the start of the Israeli operation, almost 2,000 rockets have been fired at Israel.

At least 65 Palestinians and 13 Israeli soldiers were killed in the first major ground battle of the offensive, while in one Israeli strike, 25 people were buried under the rubble of a home in the southern town of Khan Younis, including 24 from the same family.

A message on the official Twitter feed of the Israel Defence Forces showed a doctored picture of missiles raining down on Westminster under the text: “Hamas terrorists just fired rockets at southern and central Israel. What if they were attacking your home?”

Prime Minister David Cameron last night spoke by phone with his Israeli counterpart Benjamin Netanyahu and gave him his “strong support” for Israel’s right to take “proportionate action” to defend itself.

A Downing Street spokesman said the two leaders agreed that the only way to end the “spiral of violence” was a lasting ceasefire observed by both sides.

He said: “The Prime Minister noted the ongoing rocket attacks from Hamas and reiterated the UK’s strong support for Israel’s right to take proportionate action to defend itself from them.

“The Prime Minister expressed condolences for the deaths of Israeli troops and concern about mounting civilian casualties in Gaza.

“The Prime Minister agreed with prime minister Netanyahu that the way out of the spiral of violence was for both sides to observe a lasting ceasefire in line with the initiative that was put forward by Egypt.”

Mr Cameron’s spokesman told a Westminster media briefing: “We want to see a ceasefire. We believe that the initiative that the Egyptian government has been leading and which John Kerry is travelling to the region to discuss offers a real opportunity to bring that about.

“But for that to happen, Hamas needs to stop firing its rockets.”

Last week Deputy Prime Minister Nick Clegg said Israel’s bombardment of the Gaza Strip amounted to a “deliberately disproportionate form of collective punishment”.

Today, Mr Clegg said in a press conference: “It is simply intolerable that the people ofIsrael need to continue to live in constant fear and terror that their homes are going to be bombarded by rockets fired from Gaza. Israel has every right to defend itself from those reprehensible rocket attacks.

Bs8V1AJCQAAAztE“But equally, it is essential that Israel acts proportionately. There is now an outright humanitarian crisis in Gaza affecting thousands upon thousands of Gazans.

“The very high death toll of the civilian population in Gaza is of immense concern to us and that is why we believe, as most of the international community believes, that in the long run the security of Israeli citizens and the peace and dignity of the Palestinian people can only be guaranteed through a proper two-state solution. That is the only long-term solution.

“Violence begets violence. Yet another cycle of violence in Gaza will not provide the security which everybody craves in the region.”

Mr Clegg described the situation of ordinary Palestinians, who have lost loved ones and homes and been forced to live without adequate supplies of food, water and electricity in Gaza, as “a form of collective suffering for the sins of Hamas, who are unacceptably firing rockets into Israel”.

In a speech in London, the Middle East peace envoy of the Quartet – the US, EU, UN and Russia – Tony Blair said: “I am sad and angry about the tragedy of the Gaza conflict, its people pawns in a wider struggle, hundreds of Palestinians – including many children – losing their lives in this nightmare.

“I witness the fear and insecurity of Israelis who still see their right to exist under challenge. I long to see two peoples and two states side by side in peace.”

Mr Blair added: “It is vitally important that we put in place a long-term solution for Gaza.”