Foreign Secretary William Hague has urged both Israel and the Palestinians to make efforts to halt the violence in Gaza, but made clear that he believes Hamas bears the greatest responsibility for the current crisis, as well as the ability to bring it most swiftly to an end.
Mr Hague was speaking during a brief lull in the violence as Egyptian prime minister Hisham Kandil visited the enclave, which has seen a deadly exchange of rockets and airstrikes in recent days.
Prime Minister David Cameron on Thursday night spoke by telephone with his Israeli counterpart Benjamin Netanyahu to discuss the situation following Israel's assassination of Ahmed Jabari, the Hamas military chief, in a drone strike on his car on Wednesday.
Downing Street said that the PM made clear that Hamas bears principal responsibility for the crisis, but called on Israel to do everything it could to avoid civilian casualties. The conflict has been intensifying over recent weeks, but flared up dramatically in the wake of the Israeli strikes against senior Hamas figures.
Hundreds of rockets have been fired into Israel, with three people killed in the town of Kiryat Malachi - about 15 miles north of Gaza. Palestinian militants also fired rockets at Israel's commercial and cultural capital Tel Aviv for the first time.
Israel has responded with airstrikes, with at least 18 Palestinians, including some civilians, reported to have died since Wednesday. Mr Netanyahu has warned that his country is prepared to extend its operation against Hamas, sparking fears of a repeat of the ground incursion four years ago in which hundreds died.
Mr Hague told BBC Radio 4's Today programme that there had been "a large increase" in rocket attacks on Israel from Gaza over recent weeks. He added: "What Israel has done is obviously the Israeli response to that. The thing that would bring this most quickly to an end would be for Hamas to stop launching rockets at Israel."
"But of course, there are also responsibilities on Israel. I spoke to the Israeli foreign minister yesterday afternoon to urge the Israelis to do their utmost to reduce tension, to take every opportunity to de-escalate the situation and observe international humanitarian law, to avoid civilian casualties. Both sides have a responsibility to try to bring this to an end," he said.
Downing Street said the Prime Minister and Mr Morsi "shared grave concerns" about the civilian causalities left by the escalating violence.
After a phone call between the two leaders, a No 10 spokesman said: "President Morsi shared the Prime Minister's grave concerns about the civilian casualties in Gaza and Israel and about the danger of a downward spiral of violence that would lead to further instability in the region."