ISLAMABAD,  Pakistan - Several thousand Pakistani Muslims protested across the country after Friday prayers against Israel's massive bombardment of Gaza in retaliation to Hamas attacks.

Political and religious parties staged dozens of small demonstrations across the cities of Karachi, Lahore, Peshawar, and the capital Islamabad, where US and Israeli flags were burned.

"There is so much tyranny meted out to Palestinians, nobody can tolerate it. It is a waste of life if we don't stand by the righteous," said Tahira Khan, a 50-year-old designer who joined one of several protests in Karachi attended by around 2,000 people.

Protester Shahid Husain, 47, said the leaders of Muslim nations were failing to stand up for Palestinians.

"We came to the streets to make our rulers realise that they don't need to be scared of the US and that the public wants them to be on the side of Palestine -- not Israel and America," he said from Peshawar, where police said around 20 protests were held attended by more than 5,000 people.

A few hundred people also gathered in the Afghan cities of Kabul and Jalalabad for pro-Palestinian rallies organised by Taliban authorities.

"Palestine you are not alone, we are with you," one speaker told the crowd. "We are poor, but we will do whatever we can. We can't do much today but use our feet and stand in your support."

At the weekend, Hamas gunmen killed more than 1,300 people in Israel in the deadliest attack since the country's creation in 1948.

They seized around 150 hostages -- including dozens of Israelis, dual and foreign nationals -- whom Hamas is threatening to kill.

Israel has retaliated by raining air and artillery strikes in Gaza for six days, claiming more than 1,500 lives and displacing over 400,000 people in the crowded enclave.

The Pakistan government has condemned the "indiscriminate and disproportionate use of force by Israeli authorities" and "the inhumane blockade and collective punishment by Israeli forces".

The United Nations has called on the Israeli army to rescind its order for the immediate relocation of 1.1 million people from north to south Gaza, as it relentlessly pounds the enclave.

The cramped and impoverished territory, where 2.3 million residents live on top of each other, has been under a land, air and sea blockade since 2006. Israel has now cut off water, electricity and food supplies, leaving the enclave in a state of siege.