An international organization involved in assessing post-conflict reconstruction says it will take 20 years for Gaza's battered and neglected housing stock to be rebuilt following the war between Hamas and Israel.

Palestinians gather around the remains of an office building tower that was destroyed by an Israeli air strike in Gaza City before the current ceasefire went into effect. (Mohammed Salem/Reuters) The assessment by Shelter Cluster, co-chaired by the UN refugee agency and the Red Cross, underscores the complexities involved in an overall reconstruction program for the Gaza Strip, which some Palestinian officials have estimated could cost in excess of $6 billion.

Any effort to rebuild Gaza will be hindered by a blockade imposed by Egypt and Israel since the Islamic militant group Hamas seized power in 2007. Israel has severely restricted the import of concrete and other building materials into Gaza, fearing that militants will use them to build rockets and reinforce cross-border attack tunnels.

Egypt and Norway have raised the possibility of convening a Gaza donors' conference at some point next month, but no firm arrangements have been made.

17,000 homes destroyed

With a population of 1.8 million, Gaza is a densely populated coastal strip of urban warrens and agricultural land that still bears the scars of previous rounds of fighting.

In its report issued late Friday, Shelter Cluster said 17,000 Gaza housing units were destroyed or severely damaged during this summer's war and 5,000 units still need work after damage sustained in the previous military campaigns. In addition, it says, Gaza has a housing deficit of 75,000 units.

Palestinian officials have estimated that reconstruction efforts in Gaza may cost upward of $6 billion. (Ibraheem Abu Mustafa/Reuters)

Shelter Cluster said its 20-year assessment is based on the capacity of the main Israel-Gaza cargo crossing to handle 100 trucks of construction materials daily.

The latest war began after three Israeli teens were killed in the West Bank by Hamas operatives in June, prompting Israel to arrest hundreds of Hamas members there. Rocket fire from Gaza on Israeli cities then escalated, and Israel launched a massive air and later ground campaign. The fighting lasted almost two months.

Egyptian mediators tried early on to get the sides to agree to a cease-fire. Several temporary truces were broken by Gaza militants.

Over 2,100 Palestinians, most civilians, died in the war. Israel lost 71 people, all but six of them soldiers.