KABUL — Taliban suicide bombers struck NATO fuel trucks at a key border crossing between Afghanistan and Pakistan Thursday, setting off explosions that destroyed dozens of trucks and triggering a gun battle with police guards that left all three attackers dead, officials said.
The attack underscored the instability plaguing the country and the continuing danger to the US-led mission in Afghanistan as combat forces prepare to withdraw by the end of this year.
Western officials had hoped a peaceful transfer of authority to a new president in democratic elections would help ease the transition, but instead allegations of massive fraud in the June 14 runoff vote have plunged the country into a new political crisis.
Abdullah Abdullah, who is running against Ashraf Ghani Ahmadzai, said Thursday that the Independent Electoral Commission had ignored his call to stop the ballot counting and other demands, and that he will not resume cooperation with the panel or its affiliated complaints commission.
‘‘We will not consider those two institutions as legitimate from now onwards, because of their disregard of the legitimate demands of us on behalf of millions of people of Afghanistan,’’ he said at a news conference.
Abdullah acknowledged concerns the crisis could further destabilize the country but said the responsibility for that ultimately lies with the commissions, which were appointed by President Hamid Karzai.
Abdullah, a former foreign minister who won the first round of this year’s election on April 5 but failed to gain the majority needed to avoid a runoff, said his campaign monitors had recorded ballot-box stuffing and other irregularities.
He announced Wednesday that he was suspending cooperation with the electoral commission and demanded that the commission’s chief officer, Zia ul-Haq Amarkhail, be suspended for alleged ballot tampering. The commission’s spokesman, Noor Mohammad Noor, said Wednesday that an investigation had been carried out, and that the case was being decided by the complaints commission.
Preliminary election results are not due until July 2, followed by final results on July 22. Electoral officials have said they would release partial results before that but have not yet done so.
The winner will replace Karzai, the only leader the country has known since the 2001 US-led invasion that ousted the Taliban. He was constitutionally barred from seeking a third term.
The Obama administration is watching carefully, eager to show progress in the country and get a security agreement signed after announcing it would leave 9,800 US troops in Afghanistan at the end of this year to continue training the Afghans and conduct counterterrorism missions.
Taliban spokesman Zabihullah Mujahid claimed responsibility for the attack on the NATO convoy in the eastern province of Nangarhar, which a border police spokesman said began before dawn and left 37 trucks destroyed in explosions set off by a gun battle between the militants and the guards. All three of the Taliban bombers were killed.