"Those who carried it out were people born in the US and Europe and they were trained there. They were not Afghans and they never got training in Afghanistan," he said.
"Everyone knows the pilot training was done in the US and the plan of the operation was hatched there."
The message by Hekmatyar came as Barack Obama, the US president, prepared to meet a bipartisan group of congressional leaders to discuss the US military's strategy in Afghanistan.
Obama is under growing pressure from the US public and his political opponents over the war, with the number of US military fatalities this year set to be the highest in the war so far.
In his video address, Hekmatyar also said that the outcome of recent presidential elections in Afghanistan - which have been widely criticised amid allegations of vote fraud - had strengthened the hand of Iran and Russia.
|This year is proving to be the most deadly for
US troops since the war began [AFP]
"Moscow and Tehran are benefiting. You [the US government] know very well the Kabul government is under the control of people linked to Iran and Russia," he said.
"You tricked the world and the Afghans by making a funny election show ... Hundreds of millions of dollars were spent. What was the result? You admitted 20 per cent of Afghans took part.
"You have managed through your propaganda to turn Afghans against each other through highlighting language and tribal differences.
"Moscow and Tehran have already congratulated Karzai for winning."
Nato's International Security and Assistance Force (Isaf) said on Tuesday that Hizb-e Islami fighters loyal to Hekmatyar were possibly involved in an attack in Nuristan province on Saturday, in which eight US soldiers were killed.
Hekmatyar, a Pashtun regional commander and former Afghan prime minister, has traditionally allied his forces to fighters who are opposed to the presence of foreign troops.