New York, Sep 17 (DPA) The UN Human Rights Council had given an 'unacceptable' mandate to the fact-finding mission in the Gaza Strip led by South African judge Richard Goldstone, a US diplomat said Thursday.

Goldstone's findings released this week accused both Israel and Palestinian militant groups of committing war crimes and crimes against humanity during the December-January conflict in Gaza, which the mission said killed at least 1,400 people.

Susan Rice, the US ambassador to the UN, said Washington has had 'serious concerns' about the mandate given to the four-member Goldstone mission by the Geneva-based council. The US officially took its seat in the 46-member body in early September.

'We have long expressed our very serious concerns about the mandate given by the Human Rights Council prior to our joining it,' Rice said in her first reaction to the findings by Goldstone Tuesday.