In a report released on Monday, New York-based Human Rights Watch (HRW) said security in Darfur was a "farce" with the government engaged in ethnic cleansing and rebel groups looting and abducting civilians in violation of an April ceasefire.
HRW said Sudan will take it as "an all-clear sign" to keep attacking and uprooting villagers if the UN Security Council does not force Khartoum to improve security so 1.5 million people displaced by fighting can return home.
"The danger now is the ethnic cleansing will be consolidated," HRW's Jemera Rone said in Nairobi.
"The current situation where the government says it is providing security is a farce."
The Security Council, which holds a special session on Sudan in the Kenyan capital on Thursday and Friday, had threatened sanctions earlier this year if Sudan did not improve security.
But since then, Sudan has violated the terms of the ceasefire and the spirit of Security Council resolutions that urge greater security in Darfur, HRW said.
"The government in particular has continued to use helicopter gunships in bombing attacks on civilian objects. Fighting and displacement continue, particularly in South Darfur," the report said of attacks as recent as October.
Khartoum has defended more recent attacks as legitimate responses to the rebellion.
The report says ethnic cleansing in Darfur consists of "forcibly displacing people, then preventing them from returning home safely", and says government forces raided camps with tear gas to force the displaced to relocate to areas other than their homes.
"The danger now is the ethnic cleansing will be consolidated. The current situation where the government says it is providing security is a farce"
HRW's Jemera Rone
Sudan has denied it used force in two camp raids this month.
The report also criticised the rebel Justice and Equality Movement (JEM) and the Sudan Liberation Army (SLA), saying they "have abducted civilians, attacked police stations and other government institutions and raided and looted substantial numbers of livestock and commercial goods".
The SLA is also using male soldiers under the age of 18, but the group told rights investigators they are only used for sentry duty and not combat.
Any UN resolution must be backed up by concrete enforcement that can be carried out against Sudan and the rebels, the New York-based rights group said.
Aid groups' plea
Also on Monday, six other aid groups joined in the call.
"Previous UN resolutions on Darfur have amounted to little more than empty threats, with minimal impact on the levels of violence," said a statement from Care International, Oxfam International, Christian Aid, Save the Children UK, Tearfund and the International Rescue Committee.
The civil war in Darfur erupted in 2003, when two rebel groups rose up against the government they said was neglecting the vast west of Sudan.
"[Drafur rebels] have abducted civilians, attacked police stations and other government institutions and raided and looted substantial numbers of livestock and commercial goods"
Human Rights Watch report
Government attacks followed and critics say Khartoum armed nomadic tribesmen to put down the rebellion by proxy.
Peace talks to end what the United Nations calls the world's worst humanitarian crisis concluded last week after Sudan and the rebels signed security and humanitarian protocols.