The ceasefire between Israel and Palestinian militants in the Gaza Strip continued to unravel on Friday, as several Israeli towns close to the territory came under attack from rockets and mortars.

The two sides have been trading attacks since early last week, when an Israeli military incursion into Gaza killed six militants belonging to Hamas, the Islamist group that controls the territory. Gaza-based groups responded with a barrage of rocket and mortar fire, and the violence escalated further when a second Israeli incursion claimed the lives of four more Palestinian militants this week.

The Israeli government said it was keen to restore calm to the region, adding that its initial attack on Gaza was aimed at destroying a tunnel designed to facilitate the abduction of Israeli soldiers or civilians. ”We acted to neutralise a specific threat with a surgical incursion,” a government spokesman said.

Since the latest flare-up on November 4, Israel has also closed all entry points into the Gaza Strip, preventing supplies from reaching the territory’s 1.5m inhabitants. The only power station in the strip ceased operating on Thursday, plunging large parts of the strip into darkness.

Supply shortages on Friday forced the United Nations agency responsible for providing aid to the Palestinians, UNRWA, to stop handing out food aid to 750,000 Gazans.

Chris Gunness, a spokesman for UNRWA, said: ”The message today is simple and clear. We have no food, our warehouses are empty, people will start to go hungry. Hungry and desperate people on the borders of Israel are not in the interests of peace.”

He added: ”The UN at every level condemns the rockets. I again condemn them now. But more than half of the Gaza strip are children. They, the elderly, the sick, the babies, the disabled, the blind the deaf must not be punished because of the actions of the few.”

The European Union, which is responsible for fuel imports into the Gaza Strip, also voiced concern. Benita Ferrero-Waldner, the EU external relations commissioner, on Friday called on Israel to re-open the crossings for deliveries of fuel and basic humanitarian assistance, saying she was ”profoundly concerned about the consequences for the Gazan population of the complete closure of all Gaza crossings”.

The Israeli government said it was committed to prevent a humanitarian crisis from developing in the Gaza Strip.

But a government spokesman cautioned that it was ”not logical to expect that while there is combat going on that there can be a normal functioning of the crossing”.