Hurricanes Gustav and Ike have between them inflicted the worst storm damage in Cuba's history, the government says.
The storms - which hit within two weeks of each other - have caused some $5bn (Ј2.8bn) of damage, affecting nearly 450,000 homes, officials said.
At least 200,000 Cubans lost their homes and crops have been destroyed.
Analysts say the impact of the storms will make it difficult for President Raul Castro to fulfill his pledge to improve living conditions in Cuba.
The Cuban sugar ministry had already reported that Hurricane Ike had destroyed 340,000 hectares of sugar cane - nearly half the annual crop.
'Most devastating'
The government presented its preliminary report on the extent of the storm damage on Cuban state TV on Monday.
Gustav and Ike were described as "without a doubt" the most devastating hurricanes ever to have hit Cuba.
"Building and rehabilitating will mean financial investments and resources truly worth multi-millions and will require years of tense work," the report said.
As well as some 200,000 people left homeless, hundreds of thousands more may need temporary accommodation while repairs are carried out.
The storms also damaged Cuba's infrastructure, including its power grid, road network, schools and hospitals.
Gustav hit Cuba on 30 August before carrying on across the Gulf of Mexico and making landfall near the US city of New Orleans.
Just over a week later, Ike first pounded Cuba's eastern coast and then made a second landfall in the western Pinar del Rio region. The capital, Havana, suffered minor damage.
US embargo
On Monday, the US government said it had raised its initial offer of $100,000 aid for Cuban hurricane victims to up to $5m, but Cuba had rejected it.
Cuban state television, quoting a diplomatic cable, said that the government had responded that Cuba "could not accept a gift" while under a US embargo.
The Cuban government had asked the US to consider lifting its 46-year-old trade embargo for at least six months to allow it to buy materials needed for reconstruction, state TV reported.
Washington has said it will not change its policy on the embargo, imposed on Cuba since 1962, but will give some aid to non-governmental organisations that are helping Cubans.
Russia, Spain and Brazil have already sent planes carrying humanitarian aid and more is expected from regional ally Venezuela.
(BBC)
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