KABUL, Afghanistan – The United Nations reported Saturday that insurgent violence has risen sharply in Afghanistan over the last three months, with roadside bombings, complex suicide attacks and assassinations soaring over last year’s levels.

The three-month report by U.N. Secretary-General Ban Ki-moon to the U.N. Security Council appeared at odds with Pentagon assertions of slow but steady progress in Afghanistan – an assessment that was challenged by U.S. lawmakers during recent hearings on Capitol Hill.

In the report, Ban said the overall security situation in Afghanistan has not improved since his last report in March and instead the number of violent incidents had “increased significantly compared to previous years and contrary to seasonal trends.”

The most “alarming trend” was a sharp rise in the number of roadside bombings, which soared 94 percent in the first four months of this year compared with the same period in 2009, Ban said.

Moreover, assassinations of Afghan government officials jumped 45 percent, mostly in the ethnic Pashtun south, he said. NATO has launched a major operation to secure the biggest southern city, Kandahar, the Taliban’s spiritual birthplace.

At the same time, suicide attacks are occurring at the rate of about three per week, Ban said, half of them in the south. Complex attacks employing suicide bombers, rocket-propelled grenades and small arms fire were running about two a month, double the number in 2009, he added.

During testimony Tuesday before the Senate Armed Services Committee, senior Pentagon official Michele Flournoy said the percentage of complex attacks had fallen steadily since a peak in February and were averaging below last year’s levels. She gave no figures.

“The shift to more complex suicide attacks demonstrates a growing capability of the local terrorist networks linked to al-Qaida,” Ban said.

He attributed the rise in violence to increased NATO and Afghan military activity in the south during the first quarter of the year, including the U.S.-led attack on the Taliban stronghold of Marjah. He also cited “significant anti-government element activities” in the east and southeast of the country.

“The majority of incidents continue to involve armed clashes and improvised explosive devices, each accounting for one-third of the reported incidents,” Ban said, referring to the military term for roadside bombs.

The U.N. report found some encouraging signs, including the government’s plan to reach out to insurgents and offer economic incentives to leave the battlefield. It also said the U.N. was working with Afghan officials to prepare for parliamentary elections in September.

Polio vaccinations began in February to reach 7.7 million children this year, 200,000 more than last year, the report said.

Nevertheless, the overall U.N. assessment contrasted with the tone set last Wednesday by Defense Secretary Robert Gates, who told a Senate panel that the U.S.-led force was making progress in Afghanistan. Gates complained about negative perceptions about the war taking root in Washington.

“I think that we are regaining the initiative,” Gates told the panel. “I think that we are making headway.”

Key congressional Democrats responded skeptically to Gates’ remarks, raising questions about rising U.S. casualties and the slow pace of progress in an increasingly unpopular war.

At least 53 international troops, including 34 Americans, have died so far this month, a rate that could make June among the deadliest for U.S. and other international forces in the nearly nine-year war. The deadliest month for U.S. troops was October 2009, when 59 Americans died. The deadliest for the entire international force was July 2009 when 75 troops, including 44 Americans, were killed.

The U.N. also reported 395 war-related civilian casualties between April and June, a decrease of 1 percent from the same period last year. The report blamed “anti-government elements” for about 70 percent of the civilian casualties, up 3 percent from the last U.N. study in March.