Afghanistan has improved voting procedures to ensure April's presidential election is not plagued by the complaints of irregularities and fraud that marred the 2009 vote, a senior official said yesterday.

But Yousof Nooristani, head of Afghanistan's Independent Election Commission, said he feared violence could disrupt the first democratic leadership transition in Afghanistan's history.

"We have learned good lessons from past mistakes... or weaknesses," Nooristani told Reuters. "We have adopted a number of mechanisms to prevent or mitigate fraud. It will not be possible to rule it out, but we will try to mitigate as much as possible," he said.

New measures include improved training for electoral officials to deal with fraud, more secure handling of voting materials and simpler ballots, a key issue in a country where just 28% of people are literate.

The polls occur at a delicate moment as Nato withdraws, despite ongoing violence, and a standoff continues between Washington and President Hamid Karzai over a pact to permit some US troops to stay into next year.