KABUL border has been foiled, the alliance said on Monday.
The International Security Assistance Force (ISAF) media office in the east said the incident that took place at the Torkham dry port was being investigated.
Without giving further details, the NATO-led force denied the involvement of any militant activity in the poisoning conspiracy.
However, a Taliban spokesman, Zabihullah Mujahid, claimed the fighters had poisoned the meals for US troops through their Afghan cook at the military base, killing five soldiers.
The cook had escaped and rejoined the Taliban, he said, adding the scheme was in retaliation for the desecration of the Quran by US troops on the Bagram Airbase.
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