The Afghan Taliban said on Monday next month's presidential election was being manipulated by the United States, which had already chosen the winner, and threatened to use "full force" in attacking anyone taking part.
Two campaign workers have already been killed and at least one presidential candidate has been assaulted during campaigning for the April 5 poll, the first democratic transition of power in the country's history.
The Taliban said the proceedings were being stage-managed by the United States.
"The people should realise that the election will bear no result because the real elections have taken place in CIA and Pentagon offices and their favourite candidate has already been chosen," the Taliban said in a statement.
"...All fighters are given orders to disrupt this sham elections by full force and bring under attacks election workers, activists, volunteers and those providing security everywhere. If someone takes part in this (election), they will be responsible for the bad consequences themselves."
Dozens of Afghan security forces and civilians were killed on the day of the 2009 presidential election, which saw the return of incumbent Hamid Karzai to power. He is barred from running for a third term.
The vote is taking place against the background of a stagnant economy and concerns over Afghanistan's long-term security.
NATO is due to withdraw its troops by the end of the year, but a small continent of U.S. troops may remain behind to help with training, logistics, medical and air support if the next government signs a deal to let them stay.
Karzai has so far refused to sign the deal, putting billions of dollars in aid to the Afghan security forces at risk and raising doubts over the long-term ability of the military to co-ordinate the fight against the Taliban.
Government security forces were not immediately available to comment on the Taliban threat, but have hired thousands of Afghans to work as security guards at the polls and search voters for bombs or weapons.
Karzai's brother registered as a candidate, but recently announced that he would support another Karzai ally, former foreign minister Zalmay Rassoul, in the vote.
His main rivals are considered to be Abdullah Abdullah, a former aide to Afghanistan's most famous anti-Taliban militia leader, and former finance minister Ashraf Ghani.
But campaigning was interrupted after the government declared three days of national mourning following the death of Vice President Marshal Mohammad Qasim Fahim on Sunday from natural causes.