Afghan security forces seized more than 22 tons of explosives, enough to make hundreds of bombs, the interior ministry said on Tuesday, four days before a presidential election.
Taliban insurgents have declared war on the April 5 vote, calling it a western-backed sham and threatening to disrupt it.
"This discovery will prevent hundreds of bomb attacks and would have a significant impact on the overall security of the elections," Sediq Sediqqi, an Interior Ministry spokesman, told Reuters.
Sediqqi said the explosives, hidden in some 450 bags, were seized from a basement in the relatively peaceful Northern province of Takhar, where the Taliban have gained ground in recent years.
Major cities have been placed on high alert this week with 352,000 security forces deployed around the country to prevent attacks on polling stations and other installations.