By Jannat Jalil
The New York-based group, Human Rights Watch, has accused insurgents in Iraq of committing war crimes, by targeting Iraqi civilians.
About 80 people were killed by a car bomb in the holy city of Najaf
The condemnation comes as 15 people were killed in suicide bomb attacks on two police stations.
Human Rights Watch says there is a rising number of attacks on civilians who are perceived to be working with the Americans in Iraq.
These include attacks on government offices, hotels and police stations.
Human Rights Watch says these should be forbidden targets, as civilians are likely to be in them.
The group says international humanitarian law absolutely prohibits killing civilians, whatever side they are on.
But insurgents have warned they will attack anyone they see as working for the US-led occupation.
MAJOR POST-WAR ATTACKS
12 November: 26 die in suicide attack on Italian police base in Nasiriya
2 November: 16 US soldiers die as Chinook helicopter downed
27 Oct: Red Cross and other buildings in Baghdad bombed, more than 30 killed
12 Oct: Baghdad Hotel bombed, six dead
9 Oct: Police station in Baghdad bombed, 10 killed
29 Aug: Mosque near Najaf bombed, dozens dead including Shia Islam's top cleric in Iraq
19 Aug: UN headquarters in Baghdad bombed, 23 killed including head of mission
7 Aug: Jordanian Embassy bombed, 14 killed
They have already assassinated several high-profile Iraqis, including the Shia leader, Ayatollah Muhammad Baqr al-Hakim, and one of the few women on the US-appointed Iraqi Governing Council, Aqila al-Hashimi.
Suicide attacks on the Baghdad offices of the United Nations and the International Committee of the Red Cross have forced both organisations to drastically scale down their operations in Iraq.
And the mounting number of American casualties has led to the US unveiling a new faster timetable for handing over power to a sovereign Iraqi government, possibly by June next year.