Tens of thousands of pro-Palestinian demonstrators marched through central London on Saturday, demanding Britain take a tougher line against Israel over its military assault on Gaza.

The Palestinian Solidarity Campaign said 150,000 people attended the march, the third major demonstration for Gaza in London in the past four weeks.

Tens of thousands of demonstrators marched through Cape Town on Saturday to protest Israel's military assault on Palestinians in Gaza, in one of the biggest rallies in the city since the end of apartheid.

Demonstrators carried posters stating "Israel is an apartheid state" and "Stop Israeli murder".

A seven-year blockade on the Gaza Strip must end to enable reconstruction and a political solution must be found to resolve the conflict, a U.N. official said on Saturday.

"Huge swathes of Gaza have been leveled. We cannot rebuild it with our hands tied behind our backs," said Chris Gunness, spokesman for the U.N. agency for Palestinian refugees (UNRWA).

Israeli warplanes pummeled Gaza with 50 air strikes that killed eight Palestinians Saturday as militants slammed 24 rockets into Israel amid mounting calls for a fresh ceasefire.

Britain, France and Germany on Saturday urged Israel and Hamas to agree a truce at once.

Israeli warplanes Friday pounded targets across Gaza, killing at least five Palestinians, and militants fired dozens of rockets into Israel after attempts to extend a three-day truce stalled.

The month-long conflict flared once again after mediators tried but failed to extend a ceasefire that expired at 0500 GMT as Palestinian militants shattered the quiet with pre-dawn rocket attacks.

Cradling his baby daughter, Saeed Masri took flight Friday from renewed Israeli bombardment of Gaza with little faith that even a U.N. facility can protect his family.

Three hours after a temporary ceasefire between Israel and Hamas ended, a missile hit the roof of a building opposite the apartment in Jabaliya where he was staying with relatives after his own neighborhood was shelled.

The vast majority of rockets fired by Hamas at Israel over the past month were made in Gaza using civilian materials, a senior Israeli military official said Thursday.

The coastal Palestinian enclave was the setting for the 28-day conflict with Israel, during which Israel set out to seriously impair the Islamist movement's military abilities.

A spokesman for Hamas's armed wing, the Ezzedine al-Qassam Brigades, warned Thursday of renewed fighting with Israel if talks in Cairo to extend a 72-truce in Gaza collapsed.

"We appeal to the Palestinian delegation to not accept a ceasefire, unless it satisfies the demands of our people," a spokesman using the nom-de-guerre Abu Obeida said in a televised address, adding that Hamas fighters were "ready to return to battle."

The scale of civilian losses during the four-week conflict in the Gaza Strip must not happen again, the head of the International Committee of the Red Cross said on Thursday.

Speaking to reporters after visiting Gaza, ICRC President Peter Maurer said he was "deeply distressed and shocked to see the impact of violence on the civilian population".

British aid agencies launched an emergency appeal on Thursday for people affected by the conflict in Gaza, with the BBC agreeing to show adverts calling for donations -- five years after it refused to participate in a similar drive.

The Disasters Emergency Committee (DEC), which brings together 13 leading British charities at times of crisis, said half a million people in Gaza have been forced from their homes, and that up to 1.5 million have limited access to water, sanitation or medical care.