Israel's blockade of Gaza has made it impossible for the territory to recover from last year's conflict, according to Christian Aid.
Israel launched Operation Protective Edge on July 8, 2014 in response to rocket fire into Israel by militants in the Gaza Strip.
More than 2,100 Palestinian civilians died in the 50-day conflict, most of them civilians and more than 500 of them children. Israel put the number of its dead at 67 soldiers and six civilians.
More than 12,000 homes were destroyed in Gaza and 100,000 damaged. Christian Aid says that more than 100,000 people remain homeless. Electricity and water supplies are still severely limited, schools and health facilities urgently need rebuilding and the unemployment rate is now among the highest in the world, with almost 68 per cent of those under 24 jobless.
William Bell, Christian Aid's policy and advocacy officer, said: "Thanks to the generosity of the British public and the tremendous work of our partners in Gaza, the Christian Aid Gaza Crisis Appeal has reached 115,000 people and continues to help tens of thousands more by providing water, food, shelter, agricultural rehabilitation, counselling and healthcare.
"But the level of need remains endemic. Restrictions on materials entering Gaza isolate it from the West Bank and the rest of the world. The blockade has helped to create some of the highest unemployment and aid dependency levels in the world, and must be brought to an end."
Restrictions on the movement of materials into Gaza means that less than one per cent of those needed to rebuild houses destroyed and damaged during hostilities have been obtained.
Since 2007 the blockade has cut Gaza's GDP by 50 per cent. Last year's conflict led to a further decline of about $460 million, with construction, agriculture, industry, and electricity sectors affected the most, according to the World Bank statistics.
According to Oxfam, the lack of opportunities is forcing a growing number of young people to risk their lives or arrest by trying to climb the border fence into Israel to look for work.
The slow pace of reconstruction – estimated to take more than 70 years – means teenagers in Gaza will be old by the time it is completed, the agency said.
Additional reporting by Reuters.