Confidential UN maps show a clear deterioration in security in parts of Afghanistan over the course of this year, despite White House claims its strategy is working, the Wall Street Journal reported on Monday.
The paper compared two UN maps, one showing the situation at the start of this year's fighting season in March and the other towards its end in October.
While the situation in the south, the fiercest battleground between US-led troops and the Taliban remained virtually unchanged at "very high risk", it worsened in 16 districts in the north and east, the paper said.
US President Barack Obama released his review of strategy in the war earlier this month, a year after ordering 30,000 extra troops into battle to prepare for a planned security handover to Afghan forces in 2014.
Obama described the strategy as "on track" but warned that gains were fragile.
A limited withdrawal of troops is expected to start in July 2011.
There are around 140,000 US-led NATO troops in Afghanistan, two-thirds of whom are from the United States, fighting a nine-year Taliban insurgency.
The Wall Street Journal said the October map had upgraded to "high risk status" 16 districts in the north and east of Afghanistan which had previously been seen as more secure.
The districts were in the provinces of Badghis, Sari Pul, Balkh, Parwan, Baghlan, Samangan, Faryab, Laghman and Takhar.
The paper added that only two districts previously deemed high risk, one in Kunduz in the north and another in Herat in the west had received a safer rating in October.
Analysts warn that violence in the north is getting worse despite the Taliban insurgency having its powerbase in the south.
The United Nations uses the maps to assess the dangers of travelling and running schemes across Afghanistan, the Wall Street Journal said.
A UN spokesman in Afghanistan said he had not seen them when contacted by AFP.