A senior security official in Kabul denied the arrests, insisting the explosives at the centre of the scare had been planted by a police officer hoping to persuade his seniors into giving him a pay rise.

"The tanker came from Pakistan and the drivers are being held while the situation is being investigated," said International Security Assistance Force (ISAF) spokesman Major Gordon Mackenzie.

He said nine sticks of dynamite, one primed for explosion, were discovered during a search of the truck in the east of Kabul. Documents found on the vehicle indicated it was bound for Bagram Air Base, north of the city.

Bagram, which is home to some 7,000 coalition troops, is the centre of US-led operations to hunt down remaining Taliban and al-Qaeda in Afghanistan.

"It is not entirely certain the explosives were intended for use at Bagram, this is under investigation by the Afghan police," Mackenzie added.

The truck was stopped early Saturday following intelligence reports received by ISAF up to 10 days before its arrival in Kabul.

"We were unable to act on these reports until the vehicle entered our area of jurisdiction," Mackenzie said.

He added that conflicting reports from Afghan police could be due to translation difficulties but remained adamant that a potential threat had been neutralised.

But according to Kabul security commander Basir Salangi, the explosives were just a ruse concocted by local police.

"A police officer at a checkpoint put the explosives on the tanker and then informed us he had discovered them. This is purely the work of this person and the tanker and its driver have been released," he told Nampa-AFP.

"None of this is true, it is all false, no Pakistanis have been arrested. It is an attempt to enlarge something which is very simple."

Despite the confusion, the report has prompted fears that security is degenerating in war-ravaged Afghanistan.

On September 5 a massive car bomb in the Afghan capital killed 30 on the same day President Hamid Karzai survived an assassination attempt in the southern city of Kandahar.

Karzai's calls for an expansion of ISAF's role to provide countrywide security have so far gone unheeded.

On Tuesday a US State Department report, issued just days after Karzai made a direct appeal to the United Nations, indicated it was not in favour of widening ISAF's mandate beyond the Afghan capital.

bjn/sm/pch

Nampa-AFP WEB story ENDS (NAMPA 180913)

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