Violence in Afghanistan increased dramatically in the first four months of this year, the UN says.
In a quarterly report to the UN Security Council, it said roadside bomb attacks rose by 94%, compared with the same period in 2009.
On average, the report said, there were three suicide bombings a week, half of them in the country's volatile south.
The findings come amid a major Nato-led operation in Helmand and a surge of US reinforcements.
US President Barack Obama ordered 30,000 extra troops to Afghanistan in December.
Assassinations rise
And Nato launched Operation Moshtarak in Helmand province in February, its biggest military offensive since the Taliban were ousted in 2001.
The report noted the rise in violence was "attributable to an increase in military operations in the southern region during the first quarter of 2010".
It also said Afghanistan's overall security situation "has not improved" since the UN's last report in March.
Despite all this, the electoral commission had successfully registered more than 2,500 political candidates - including 400 women - for polls due in September, the report said.
It also noted that both the Afghan police and army were slightly ahead of interim targets for beefing up their ranks.
But assassinations had risen 45%, with the Taliban and others increasingly successful at killing Afghan officials, the report said.
It added that sophisticated suicide bombings had doubled from last year to roughly two per month.
"The shift to more complex suicide attacks demonstrates a growing capability of the local terrorist networks linked to al-Qaeda," the report said.
It also noted: "The alarming trend of increased improvised explosive device incidents and the occurrence of complex suicide attacks persisted".
