Palestinian human rights activists have called on authorities in the West Bank and Gaza to investigate allegations of war crimes carried out by their forces.

The accusations come from a United Nations report into the Israel's Cast Lead offensive in Gaza last year.

Palestinian militants are accused of attacking Israeli civilians, as well as torturing and executing suspected Palestinian informers.

The internal investigations must be launched by February, the groups said.

The report produced by a team led by former war crimes prosecutor Richard Goldstone accused both sides of war crimes during the Israeli military offensive in December 2008 and January 2009.

The 11 human rights groups wrote identical letters to Palestinian Authority President Mahmoud Abbas, and Hamas Prime Minister Ismail Haniya urging that they investigate the allegations against them.

Responsible

"Whereas the bulk of the [Goldstone] report addressed violations by Israel, the occupying power, it also considered violations by Palestinian armed groups and the Palestinian authorities in Gaza and the West Bank," the letter said.

"We urge you to immediately take clear and public steps toward holding to account all those who prove to be responsible for the violations detailed in the report."

In November the UN General Assembly voted in favour of a resolution calling for independent investigations into the accusations made by Mr Goldstone, a South African judge.

On 5 February the UN Secretary General Ban Ki-Moon is due to submit a report on the progress made on the General Assembly resolution.

The UN will then decide what further action to take, but unlike resolutions passed by the Security Council, General Assembly resolutions are not legally binding.

The human rights groups include two that are based in Israel, Adallah and the Arab Association for Human Rights.

Other groups, like the al-Mezan Centre for Human Rights and al-Haq, operate in the West Bank and Gaza.

In all, 18 UN member states, including the US, voted against the resolution supporting the investigations. There were 44 abstentions.

Palestinians and rights groups say more than 1,400 Gazans died in the 22-day conflict, but Israel puts the figure at 1,166. Thirteen Israelis, including three civilians, were killed.