The Israeli military made precise calculations of Gaza's daily calorie needs to avoid malnutrition during a blockade imposed on the Palestinian territory between 2007 and mid-2010, according to files the defence ministry released on Wednesday under a court order.

Israel says it never limited how many calories were available to Gaza, but critics claimed the document was proof the government limited food supplies to put pressure on Hamas.

At the height of the blockade Israel also maintained a list of foods that were permitted and banned from Gaza.

Major Guy Inbar, an Israeli military spokesman, said the calculation, based on a person's average requirement of 2,300 calories a day, was meant to identify warning signs to help avoid a humanitarian crisis, and that it was never used to restrict the flow of food.

The analysis included adjustments for local farm products as well as an assessment of the kinds of food imports needed to sustain the population.

The Israeli advocacy group Gisha, which aims to protect the rights of Palestinian residents, waged a long court battle to release the document. Its members say Israel calculated the calorie needs for Gaza's population so as to restrict the quantity of food it allowed in.

Israel imposed the blockade after identifying Gaza as a "hostile territory" in September 2007, following the takeover by Hamas. The Israeli resolution said it intended severe restrictions on civilians.

Israel said the blockade was necessary to weaken Hamas. But critics say the blockade constituted collective punishment against Gaza's population of more than 1.5 million.

A US diplomatic cable revealed by WikiLeaks last year quoted Israeli diplomats as saying they wanted to "keep Gaza's economy on the brink of collapse".

Gisha said: "The official goal of the policy was to wage 'economic warfare' which would paralyse Gaza's economy and, according to the defence ministry, create pressure on the Hamas government."

The food calculation, made in January 2008, applied the average daily requirement of 2,279 calories per person, in line with World Health Organisation's guidelines, according to the document.

"The stability of the humanitarian effort is critical to prevent the development of malnutrition," the document said.

The defence ministry handed over its document on the food calculation to Gisha only after the group filed a freedom of information petition.

Israel also used baffling secret guidelines to differentiate between humanitarian necessities and non-essential luxuries. The outcome was that military bureaucrats enforcing the blockade allowed frozen salmon and low-fat yogurt into Gaza, but not coriander and instant coffee.

To combat the blockade, Hamas built a network of tunnels through which they smuggled in food, weapons and other contraband from Egypt at inflated prices.

In Gaza, Fawzi Barhoum, a Hamas spokesman, said the document was "evidence that the Gaza blockade was planned and the target was not Hamas or the government, as the occupation always claimed. This blockade targeted all human beings … this document should be used to trial the occupation for their crimes against the humanity in Gaza".

While the embargo crippled Gaza's economy, at no point did observers identify a food crisis developing in the territory, whose residents rely heavily on international food aid.

Israel was forced to ease the land blockade under international pressure after the deadly attack on a Gaza-bound international flotilla in May 2010.

Since then consumer goods have been moving freely into Gaza from Israel, but construction materials are still largely barred entry. Israel argues that the Gaza militants could use goods like pipes and concrete in attacks on southern Israeli communities.

Israel states that the naval blockade, which remains in effect, is necessary to prevent smuggling of weapons at sea. The country also restricts exports, further constraining Gaza's economy.