The Israeli army unlawfully destroyed civilian property in its 22-day offensive in Gaza in 2008 and 2009, a report by Human Rights Watch says.

Israeli forces destroyed buildings that had "no military significance", a grave breach of the Fourth Geneva Conventions, the report said.

The New-York based group have documented 12 cases that they say must be investigated.

The IDF denies the charges and says it has investigated the incursion already.

Palestinians and rights groups say more than 1,400 Gazans died in the conflict, known as Operation Cast Lead, but Israel puts the figure at 1,166. Thirteen Israelis, including three civilians, were killed.

'IDF control'

Human Rights Watch documented the complete destruction of 189 buildings, including 11 factories, 8 warehouses and 170 residential buildings, leaving at least 971 people homeless during the operation which began in December 2008.

The 12 incidents documented in the report account for roughly 5% of the homes, factories and warehouses destroyed in Gaza during the operation the report said.

"These cases describe instances in which Israeli forces caused extensive destruction of homes, factories, farms and greenhouses in areas under IDF control without any evident military purpose," the report said.

"These cases occurred when there was no fighting in these areas; in many cases, the destruction was carried out during the final days of the campaign when an Israeli withdrawal was imminent."

The group obtained satellite pictures of Gaza during and after the conflict.

A Human Rights Watch researcher interviewed 94 people in Gaza about their experiences as they fled Israeli forces.

Majid al-Athamna who lived in the town of Izbt Abd Rabbo in the north of the Gaza Strip, told HRW that when he was allowed to return, he found his home demolished.

"There are still four Hamas houses standing on Zimmo Street, but mine is destroyed. Were my cars launching rockets? Why did they destroy them?" he said.

The other interviewees had similar stories.

Violations

Human Rights Watch say they discounted any case in which a military action occurred nearby.

The report stops short of saying outright that war crimes were committed by the Israeli Defense Forces.

But, it said, "the report examines incidents of destruction that suggested violation of the laws-of-war prohibition of wanton destruction" - the term used to describe extensive destruction of civilian property not lawfully justified by military necessity.

"Such destruction would be a grave breach of the Fourth Geneva Conventions of 1949, which is applicable in Gaza. Individuals responsible for committing or ordering such destruction should be prosecuted for war crimes," the report said.

'Carefully checked'

In an IDF report published in July into Operation Cast Lead, the military says that every consideration to protect civilians was made before opening fire.

"While Hamas deliberately sought to harm civilians by launching rockets and mortars on towns in Southern Israel, and even boasted about directing their attacks at civilian populations, the IDF carefully checked and cross-checked targets — using best available real-time intelligence — to make sure they were being used for combat or terrorist activities, and not instead solely for civilian use," the report said.

In a written response to HRW, included in their report, an IDF spokesman said "The level of damage to the infrastructure was proportional, and did not deviate from that which was required to fulfil the operational requirements."

Any fresh cases not covered by the July report would be investigated, the spokesman said.

Last year, a report produced by a UN team led by former war crimes prosecutor Richard Goldstone accused both sides of war crimes during the Israeli military offensive