Afghans vote next week to choose a president for only the second time in history in an election challenged by rising extremist violence that threatens to keep voters away in droves.
Thousands of US and NATO troops pushed into militant strongholds months before the August 20 polling day but with a week to go, around nine districts were still under insurgent control making voting unlikely, authorities said.
Incumbent Hamid Karzai has been tipped the winner but a strong campaign by former finance minister Abdullah Abdullah has raised the chance of a run-off as fears grow that charges of irregularities may lead to protests.
About 300,000 Afghan and foreign security forces --every man available officials say -- will provide security at nearly 7,000 polling stations.
"They have no chances to carry out a big attack," defence ministry spokesman General Mohammad Zahir Azimi said, referring to Taliban-led militants behind a bloody campaign that has seen record attacks this year.
The extremists, demanding a boycott of an "American process," have said they would not directly target polling centres. But an attack on provincial government and police headquarters just 50 kilometres south of Kabul on Monday reinforced fears of violence that could keep voters from casting their ballots.
About 17 millions Afghans have registered to vote, but low turnout would undermine the election's credibility.