Updated

More than 1,000 people were killed in Iraq in July, the highest monthly death toll in five years, the U.N. said Thursday, a grim figure that shows rapidly deteriorating security as sectarian tensions soar nearly two years after U.S. troops withdrew from the country.

Violence has been on the rise all year, but the number of attacks against civilians and security forces has spiked during the Islamic holy month of Ramadan, which began early last month. The increased bloodshed has intensified fears that Iraq is on a path back to the widespread chaos that nearly tore the country apart in the aftermath of the U.S.-led invasion that ousted Saddam Hussein in 2003.

Months of rallies by Iraq's minority Sunnis against the Shiite-led government over what they contend is second-class treatment and the unfair use of tough anti-terrorism measures against their sect.

The killings significantly picked up after Iraqi security forces launched a heavy-handed crackdown on a Sunni protest camp in the northern town of Hawija on April 23. A ferocious backlash followed the raid, with deadly bomb attacks and sporadic gunbattles between insurgents and soldiers — this time members of the Iraqi security forces rather than U.S. troops.

The U.N. Mission in Iraq said 1,057 Iraqis were killed and 2,326 wounded in July, the highest toll since June 2008 when 975 people were killed.

The increase was particularly troubling because the numbers had begun declining five years ago following a series of U.S.-led offensives and a Sunni revolt against al-Qaida in Iraq.

"We haven't seen such numbers in more than five years, when the blind rage of sectarian strife that inflicted such deep wounds upon this country was finally abating. I reiterate my urgent call on Iraq's political leaders to take immediate and decisive action to stop the senseless bloodshed, and to prevent these dark days from returning," acting U.N. envoy to Iraq, Gyorgy Busztin, said in a statement.

The U.N. said that 928 of those killed in July were civilians and 129 were Iraqi security forces.

In all, 4,137 civilians have been killed, most in Baghdad, and 9,865 wounded so far this year, according to the statement. That was up from 1,684 killed in the January-July period last year.

Al-Qaida in Iraq has claimed responsibility for many of the suicide attacks and car bombings in recent days as it seeks to stoke sectarian hatred and undermine Iraq's Shiite-led government. Much of the violence is targeting Shiites who have held the reins of power since Saddam's Sunni-dominated regime was ousted.

U.N. Secretary-General Ban Ki-moon last month described the scale of violence as alarming and warned that the increasingly sectarian-charged civil war raging in neighboring Syria is affecting Iraq's own political stability.

Although Iraq is officially neutral in the conflict, U.S. officials charge that it continues to allow flights suspected of carrying Iranian arms to transit its airspace. Iraqi officials have carried out some spot checks of Iranian planes and say they've found nothing. Iraqi fighters are meanwhile traveling to fight in Syria, with Shiites fighting alongside President Bashar Assad's forces and Iraq's al-Qaida arm, now known as the Islamic State of Iraq and the Levant, siding with the mostly Sunni rebels.

"Iraq has become part of the ongoing regional struggle between regional powers such as Iran, Saudi Arabia and Turkey," Baghdad-based political analyst Hadi Jalo said. "The growing power of al-Qaida-linked extremist groups in Syria is having a devastating impact on the Iraqi situation. Now the Islamic fighters have much more freedom to move across the Iraqi-Syrian borders in order to launch attacks in both countries and these groups are helping each other because they believe that they are united by one goal, which is to establish an Islamic state in Iraq and Syria and their joint aim is to destabilize both countries. "

Iraqis also blamed the government for failing to provide capable security forces to protect the people.

"We are witnessing the return of the dark days of the civil war that took place in 2006-2007 and the country is returning to square one where the armed groups have the upper hand in the country," said Riyadh Hussein, a government employee from eastern Baghdad. "We are moving in a vicious circle full of political feuds and security failures."

"The security forces have no experience or capability to stop al-Qaida, while on the other hand the armed groups are getting stronger, both in quality and quantity," he added.

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Associated Press writer Kim Gamel in Cairo contributed to this report.