The ongoing genocide in Sudan's Darfur region was the world's worst human rights abuse last year, the U.S. State Department said Tuesday in a report that also found freedoms eroding in numerous other nations, including war-torn Afghanistan and Iraq.

The 2006 Country Reports on Human Rights Practices wasreleased two days before U.S. diplomats are due to meet Sudanese President Omar al-Bashir in Khartoum.

Itlaid the blame for mass killingsof African tribesin the troubled region squarely on the Sudanese government and its proxy Arab militia, known as the janjaweed.

"The Sudanese government and government-backed janjaweed militia bear responsibility for the genocide in Darfur," said the annual survey of human rights practices, which also cited abuses by indigenous rebel groups in Darfur.

"All parties to the conflagration committed serious abuses, including widespread killing of civilians, rape as a tool of war, systematic torture, robbery and recruitment of child soldiers."

More than 200,000 people in Darfurhave been killed and 2.5 million displaced in the nearly four years of fighting, which has escalated since an accord with the rebel groups in May.

"Too often in the past year we received painful reminders that human rights, though self-evident, are not self-enforcing," Secretary of State Condoleezza Rice said at the report's release in Washington.

"We are recommitting ourselves to call every government to account that still treats the basic rights of its citizens as options," Rice said, adding the United States does not hold itself out as perfect in that regard.

U.S.-backed governments criticized

The report also sternly criticized fledglingU.S.-backed governments in Iraq and Afghanistan.

In Iraq, "both deepening sectarian violence and acts of terrorism seriously undercut human rights and democratic progress during 2006" despite enhanced securitymeasureslaunched by Prime Minister Nouri al-Maliki's government, it said.

The report said the Iraqi defence and interior ministries were also responsible for "serious" human rights violations, including severe beatings, electrocutions and sexual assaults of detainees.

The Afghan government has made "important" progress on the human rights front, but its performance "remained poor" last year, the report said, attributing lapses to a weak central administration, abuses by authorities, as well as Taliban and al-Qaeda insurgents.

Looking inward

The report also acknowledged its criticisms came at a time when the United States government's own human rights record and actions in the wake of the Sept. 11, 2001, terrorist attacks "have been questioned."

"We are also committed to continual improvement," the report said."U.S. laws, policies, and practices governing the detention, treatment and trial of terrorist suspects have evolved considerably over the last five years.

"Our democratic system of government is not infallible, but it is accountable — our robust civil society, our vibrant free media, our independent branches of government, and a well-established rule of law work as correctives."

The report also cited human rights abuses by U.S. allies Pakistan and Egypt, along with Belarus, China, Eritrea, Iran, Lebanon, Russia, Syria, Venezuela and Zimbabwe, where governments cracked down on the rights of citizens or failed to protect them from abuses.

Russia was criticized for its poor rights record in Chechnya as well as less than thorough probes of suspected contract killings of government foes, including reform-minded officials and journalists.

With files from the Associated Press