Israel is to double the amount of water it channels annually to Palestinians in the blockaded Gaza Strip, a defence ministry body said Wednesday.

A humanitarian crisis has gripped Gaza since a July-August war with Israel, which controls most of the territory's resources, its imports and exports as well as the movement of people.

The body responsible for coordinating Israeli government activity in the Palestinian territories, COGAT, said it is to increase the volume of water it provides to Gaza from five to 10 million cubic metres (175 to 350 million cubic feet) per annum, beginning within days.

The decision was in response to growing needs in the Palestinian enclave, a spokeswoman told AFP.

The severe water shortage was due to excessive overuse of groundwater resources along the coast of Gaza, she said.

The water is to flow through a new pipe already in place.

The Palestinian water authority was not immediately available for comment.

COGAT chief Major General Yoav Mordechai said he hoped "Hamas would not steal water from civilians as they steal construction materials intended for the reconstruction of houses" in Gaza.

Israel accuses Hamas, which controls Gaza, and other militant groups of using building material to build rockets and tunnels for attacking the Jewish state. As a result, it restricts the entry of building materials.

Israel and Hamas fought a devastating 50-day war in the coastal enclave that killed more than 2,200 people and left 100,000 Gazans homeless and large swathes of the territory in ruins.

The United Nations and other agencies have warned that failure to rehabilitate Gaza will lead to further conflict in the near future, and have urged Israel to lift its eight-year blockade of the enclave.

UN Middle East peace envoy Robert Serry criticised the international community Monday for failing to deliver funds pledged for reconstructing Gaza.