Six people have been killed in Gaza after Israel responded with airstrikes and tank fire to about 250 rockets being fired over the border by Palestinian militants on a day that has put further strain on an already fraying ceasefire.

It was the second day of fighting after a month-long lull in violence around the blockaded enclave and came while leaders of Hamas, the militant group that controls Gaza, were in Egypt for talks aimed at restoring the ceasefire.