The International Committee of the Red Cross highlighted the plight of millions of Iraqis who still have little or no access to clean water, sanitation or health care.
"The humanitarian situation in most of the country is among the most critical in the world," the Swiss-based agency said in a report.
"Better security in some parts of Iraq must not distract attention from the continuing plight of millions of people who have essentially been left to their own devices," said Beatrice Roggo, the ICRC's head of operations for the Middle East and North Africa.
Although security has improved in some parts of the country, the Red Cross report stressed that Iraqis were being killed or injured on a daily basis in fighting and attacks.
Civilians are often deliberately targeted, in complete disregard for the rules of international humanitarian law, it added.
A recent World Health Organisation and Iraqi health ministry report estimated that 151,000 people were killed between the start of the invasion on March 20, 2003 and June 2006.
Other estimates have put the number of civilian deaths as a result of the conflict between nearly 48,000 and as high as 601,000.
The ICRC said hospitals lacked qualified staff and basic drugs, and therefore struggled to provide suitable care for the injured. Many health-care facilities have not been properly maintained, and the care they provide is often too expensive for ordinary Iraqis.
"To avert an even worse crisis, more attention must be paid to the everyday needs of Iraqis," Roggo said. "Everyone should have regular access to health care, electricity, clean water and sanitation."
In a separate report to mark the fifth anniversary of the US-led invasion, Amnesty International said the rights situation in Iraq was "disastrous".
"Five years after the US-led invasion that toppled (former president) Saddam Hussein, Iraq is one of the most dangerous countries in the world," the 24-page report said.
Against a backdrop of insecurity, law and order and economic recovery were a "distant prospect" while most Iraqis were living in poverty, with food shortages, lack of access to safe drinking water and high unemployment.
More than four in 10 Iraqis lived on less than one US dollar a day -- the UN standard for measuring poverty -- while the health and education systems were at near collapse and women and girls at risk of violence from extremists.
"Saddam Hussein's administration was a byword for human rights abuse," said Amnesty's director for Middle East and North Africa, Malcolm Smart. "But its replacement has brought no respite at all for its people."
The failure to investigate alleged abuses "is one of the most worrying aspects for the future", he added.
"Even when faced with overwhelming evidence of torture under their watch, the Iraqi authorities have failed to hold the perpetrators to account -- and the US and its allies have failed to demand that they do so," he said.
Amnesty also criticised the extensive use of the death penalty, the international community's failure to cater for Iraqi refugees and despite the more stable situation, the lack of free speech in the Kurdistan region.
"Despite claims that the security situation has improved in recent months, the human rights situation is disastrous," the London-based group said, highlighting the kidnap, torture and murder of civilians by armed groups.
"All sides have committed gross human rights violations, including war crimes and crimes against humanity," it added, referring to militia groups, Iraqi security forces, US-led troops plus private and military security guards.
© 2008 Agence France Presse