Five individuals have been arrested and eleven tons of explosives were reported to be found in their possession.
Updated at 8:15 a.m. ET: Afghan security forces on Saturday arrested five insurgents suspected of planning massive attacks on crowded areas of the capital Kabul, an intelligence spokesman said.
S. Sabawoon / EPA
Afghan security official stands guard at the checkpoint on a roadside in Kabul on Saturday.
National Directorate of Security (NDS) spokesman Shafiqullah Tahiri said the five men were seized on Kabul's outskirts with 10,000 kilograms of explosives (11 tons) stuffed in 400 bags and hidden beneath a cargo of potatoes in the back of a Pakistan-registered truck.
The group also planned to assassinate the country's second vice-president Abdul Karim Khalili, the BBC reported.
The BBC's Bilal Sarwary reported on Twitter that a video detailing the insurgents' plan had been found.
"It could have caused large-scale bloodshed," Tahiri told a news conference in Kabul.
"Three Pakistani terrorists and two of their Afghan collaborators who placed the explosives under bags of potatoes in a truck were caught."
Tahiri said the five men confessed to receiving training from Noor Afzal and Mohammad Omar, whom he identified as key commanders of the Pakistani Taliban and Pakistan intelligence.
Video footage released by NDS to media showed the detained men, including the alleged Pakistanis, talking about where they came from while sitting against a blank white wall.
Rahmat Gul / AP
More than ten years after the beginning of the war, Afghanistan faces external pressure to reform as well as ongoing internal conflicts.
A Pakistani intelligence official declined comment on the accusations, while Afghan officials were not immediately available to give additional information.
The alleged connection to militants in Pakistan will likely step up the pressure on Islamabad, after a recent assault by insurgents on diplomatic and government areas in Kabul and elsewhere put the spotlight on the South Asian nation.
Afghan officials have long accused Pakistan of using insurgent groups like the Afghan Taliban as proxies in Afghanistan.
Pakistan's government denies supporting or giving sanctuary to insurgents on its territory.
Insurgents this week launched a coordinated assault on four provinces, targeting diplomatic and government areas of Kabul with rockets and gunfire in what they said was retaliation for abuses of Afghans by U.S. soldiers.
The attacks showed the insurgency's resilience nearly 11 years since the Afghan Taliban were toppled.
The Afghan Taliban claimed responsibility for the attacks and said it planned similar assaults in coming months.
Reuters contributed to this report.