The first six months of 2011 were the deadliest for civilians in Afghanistan since the war began in 2001, a UN report has found.
The country saw 1,462 civilian deaths in January to June, a 15% increase on the same period last year.
Most of the deaths were caused by roadside bombs and anti-government forces such as the Taliban.
While the total number of people killed by pro-government action fell by 9%, more people died in Nato air strikes.
The report comes days before Nato is due to begin the process of handing over responsibility of some provinces to Afghan security forces.
On Wednesday night, at least six people were killed in a Nato raid on a house in Matun, in Khost province - local people said all those killed were civilians but Nato said they were insurgents.
"The rising tide of violence and bloodshed in the first half of 2011 brought injury and death to Afghan civilians at levels without recorded precedent in the current armed conflict," the UN's annual mid-year report said.
Of those deaths, 80% have been blamed on anti-government militants including the Taliban, with roadside bombs and IED [improved explosive devices] the single biggest killer.
There has also been an increase in the number of deaths caused by suicide attacks. The report also warned that while the number of suicide attacks was largely unchanged, the number of casualties they caused caused had gone up 53%.
Such attacks were now "more complex", said the UN, and often involved "multiple bombers in spectacular attacks that kill many Afghan civilians".
The UN said the violence rose "as insurgents sought to demonstrate that Afghan security forces could not manage security on their own".
Pro-government forces were responsible for 14% of the total number of civilians killed.
Nato air strikes were once again the leading cause of these casualties, leaving 79 Afghans dead in the period in question.
More than half of those deaths have been attributed to the use of Apache ground attack helicopters.
Night raids carried out by the US-led forces led to 2% of civilian deaths, a slight decrease on 2010.
The raids are controversial and President Hamid Karzai has warned they encourage sympathy with insurgents forces.
The report warned that "resentment regarding these raids" had grown among the Afghan population and were often followed by often deadly violent protests.
The UN said it had been unable to collect any data in the northern regions between March and June, as its Mazar-e Sharif base was forced to close following an attack which killed eight aid workers.
The director of communications for the UN in Kabul, Kieran Doyle, told the BBC that the casualty figures were not surprising but were still alarming.
He said fighting had been expected to intensify given the recent surge in international troop numbers and the Taliban's declaration of a "Spring offensive".
The BBC's Jonathan Beale in Kabul says that despite claims from Western leaders of progress and improving security in Afghanistan, these figures show increasing violence in the everyday lives of Afghans.