So-called "night letters" or leaflets, left on the ground in villages in southern Afghanistan, threaten that the Taliban will cut off the noses and ears of those who vote on Thursday.
"In order for them to not get hurt, we are saying to them to not go to the polling stations or close to the Afghan and foreign forces, for we will carry out suicide attacks or even direct attacks against them," a Taliban spokesman told the Reuters news agency by phone from an undisclosed location.
"We are using new tactics targeting election centres ... We will accelerate our activities on election day and the day before," Qari Yousuf Ahmadi said.
The latest attacks came as the government of Hamid Karzai, the incumbent candidate, allowed the return of Abdul Rashid Dostum, an exiled veteran politician known as a kingmaker, in an apparent attempt to shore up support and avoid a run-off for Karzai.
Dostum's supporters, who gave him 10 per cent of the vote in the 2004 election, had threatened to withdraw their backing for Karzai in Thursday's polls unless the former Uzbek general was allowed to return.
Opinion polls indicate Karzai has a strong lead – around 45 per cent – but may not win the 50 per cent necessary to avoid a run-off against his strongest challenger, Abdullah Abdullah, a former foreign minister.
And a run-off could see his opponents – now spread out in their support for 35 challengers - uniting behind a single contender.
Dostum had been in Turkey since last year when the Afghan government released him from house arrest imposed for fighting with a rival.
|The Taliban has warned it will cut off the noses, ears and fingers of those who vote [AFP]
It was never made clear if Dostum's exile was ordered or self-imposed but on Sunday a government statement said there was no legal reason to prevent him from returning.
Aminullah Habibi a research fellow at the British Defence academy, who fled Afghanistan in the late 1990s, told Al Jazeera that Karzai "cannot ignore" Dostum's supporters.
"Afghanistan is ethnically a divided society; politics is defined on the line of ethnicity."
Dostum was a key part of the alliance that toppled the Taliban in 2001, but has been accused by human rights groups of widespread abuse, including allowing the massacre of several thousand prisoners during his watch.
A US official at the Kabul embassy condemned his return on Sunday and said there was concern over the timing.
"We have made clear to the government of Afghanistan, our serious concerns about the prospective role of Mr Dostum in today's Afghanistan and particularly during these historic elections," the official said.
"The issues surrounding him become all the more acute with his return to Afghanistan during this period."
Sunday also saw Karzai pledging to rein in the operations of international forces as he held a televised debate with two rivals, Ramazan Bashardost, an independent candidate, and Ashraf Ghani, a former finance minister.
Al Jazeera's James Bays, reporting from Afghanistan, said Karzai pledged to make some big changes if re-elected, the most significant of which concerned foreign forces.
"He said that there will be no military operations by international forces if they were not first permitted by Afghans.
"He said he would not allow international forces to search Afghan homes. And he said he didn't want any Afghans in the future to be held in jails run by foreigners.
"So that means that controversial prison base at Bagram airport - which lots of human rights organisations have been talking about - will have to close."
Sunday's deaths of the three British soldiers who were on patrol near Sangin, in Helmand province, brought to 204 the total number of British troops killed in Afghanistan since the UK joined the US-led invasion to topple the Taliban in 2001.
July was the deadliest month so far, with 21 soldiers killed.
Campaigning ends at midnight on Monday, before about 17 million eligible voters out of Afghanistan's 33 million population, head to the polls on Thursday.