British-Lebanese human rights lawyer and George Clooney's fiancée Amal Alamuddin has declined to be part of a three-member UN team to probe alleged Israeli war crimes in Gaza, citing prior commitments.

The UN panel will look into the actions of Israel Defense Forces (IDF) in West Bank, Gaza Strip and east Jerusalem for any violations of international law.

Turning down the offer from the United Nations Human Rights Council (UNHRC), the Lebanese- born lawyer said: "I am horrified by the situation in the occupied Gaza Strip, particularly the civilian casualties... and strongly believe that there should be an independent investigation and accountability for crimes that have been committed."

"I am honoured to have received the offer, but given existing commitments – including eight ongoing cases – unfortunately could not accept this role."

It is still unclear who will be replacing her in the team. The other two members are Doudou Diene of Senegal, a human rights veteran who was also involved in probing the post-war scenario in Ivory Coast, and Canadian lawyer William Schabas, the chief of the panel.

The team will be asked to file its report with the UNHRC in March 2015

Meanwhile, Tel Aviv has lambasted the UN for appointing fierce critics of Israel to the panel and called the UNHRC a "kangaroo court".

"When the decision about the creation of the committee was made on 23 July, the prime minister and foreign ministry announced that the Human Rights Council had long ago become the Terrorists' Rights Council, a kangaroo court in which the results of its 'investigations' can be predicted in advanced," Israel's foreign ministry said in a statement.

On the other hand, Hamas has welcomed the UN probe initiative.