israel gaza airstrikes
Palestinians watch as rescue workers search for victims under the rubble of a house destroyed in an Israeli air strike (Reuters)

The head of a UN inquiry into the 2014 conflict between Israel and Gaza has quit over bias claims made by Israel.

William Schabas was appointed to lead a three-member group into an inquiry on alleged war crimes committed by Israel during its Operation Protective Edge carried out last summer.

The commission is looking into the behaviour of both the Israel Defense Forces (IDF) and Hamas, the Islamist movement in Gaza.

Schabas was accused by Israel of being biased after he carried out some consultancy work for the Palestine Liberation Organisation, which aims to achieve the "liberation of Palestinian territories", Reuters reported.

In a letter to the commission, Schabas said he would step down immediately to prevent the issue from affecting the preparation of the report and its findings, due to be published in March.

Schabas' resignation came a few weeks after the International Criminal Court (ICC) announced it had started an "impartial" preliminary investigation into war crimes allegations against Israel arising from the Protective Edge campaign.

In his letter, Schabas said that a legal opinion he wrote for the Palestine Liberation Organisation in 2012, for which he was paid $1,300 (£865), was not different from advice he had given to many other governments and organisations.

"My views on Israel and Palestine as well as on many other issues were well known and very public," he wrote. "This work in defence of human rights appears to have made me a huge target for malicious attacks."

Protective Edge was launched on 8 July to restore calm in southern Israel after Gaza had launched some 150 rockets into the country.

The IDF operation was initially a purely aerial offensive, before expanding into a ground invasion aimed at finding and destroying Hamas' underground tunnels.

The operation caused the death of more than 2,200 Palestinians, mainly civilians, and 71 Israelis, of whom 66 were IDF soldiers.