Rescue teams are working to help thousands of Palestinians evacuated from their homes after heavy flooding hit the Gaza Strip.

The United Nations has declared a state of emergency in the war-torn coastal enclave following torrential rains this week.

Among those affected were families who had lost their homes during the war between the Islamist Hamas movement, which controls Gaza, and the Israeli army during the summer.

More than 2200 people, mostly Palestinian civilians, died in the conflict.

"We have been homeless for more than three months," said Na'eem Jendeya, a resident of Sheja'eya neighbourhood in Gaza city, one of the hardest hit regions during the war.

"Now our suffering increased due to the heavy rain," he added.

The United Nations agency for Palestinian refugees, UNRWA, said the rains were making an already difficult humanitarian crisis worse.

The agency shut down 63 schools in Gaza City alone as a precautionary measure.

Robert Turner, chief of UNRWA operations in Gaza expressed deep concerns in an official press statement.

"We are very concerned about such severe storms this early in the season and on the back of unprecedented damage and destruction caused by the recent conflict," he said.

"We are particularly concerned for those families still seeking adequate shelter and preparing for the winter months, and for the impact the flooding is already having on children unable to attend school," he said.

Tens of thousands of homes were made unlivable during the 50-day war, while many others were badly damaged.

Palestinian officials say they are hoping to be granted permission to import construction materials to begin rebuilding.

However, Israeli authorities often block such imports, saying they could be used to build weapons systems.