Afghanistan's police force has said that a Pakistani army officer is among the men arrested after it broke up a group planning to carry out suicide attacks in Kabul.
Security has been stepped up in the capital, despite the fact that the alleged plot appears to have been foiled.
"Just a couple of days ago the police arrested 16 people. Nine of them were actually suicide bombers, all trained outside of Afghanistan," Mohammad Hanif Atmar, the Afghan interior minister, told Al Jazeera.
Asked whether he saw evidence of the involvement of Pakistan or parts of the Pakistani security forces in the alleged plots, Atmar said: "The evidence speaks for itself.
"We are investigating into this matter and we will be soon talking to our Pakistani colleagues.
"And then basically [we will] show this evidence to them and say is this happening based on a policy or is it just a couple of rogue people doing this."
But Pakistan rejected the accusations, aired exclusively by Al Jazeera on Saturday.
General Athar Abbas, the Pakistan army spokesman, dismissed the claim that a Pakistani army captain was among the suspects "baseless and fabricated."
Pakistan is under international pressure to deal with Taliban and al-Qaeda groups which hide out in the country's northwest tribal regions, from where they launch frequent attacks on Nato troops in bordering Afghanistan.
Al Jazeera was allowed to film five of the suspects accused of attempting to get suicide bomb vests into Kabul, but the man authorities said was a Pakistani soldier was not among them.
Al Jazeera's James Bays, reporting from the capital, said that the men, who had their heads covered, looked young, with some of them possibly under 18-years-old.
Videos released by the authorities of other suspects showed prisoners to have suffered injuries. Police said that the injuries were sustained during their arrest, not during interrogations.
Afghan forces have said that the arrests showed that tightened security around the capital was having some success in preventing attacks.
Imtiaz Gul, a political analyst and author of The Al Qaeda Connection, told Al Jazeera: "Military officials in Pakistan are ignorant of these arrests so it is still a wait and see game".
"Pakistani officials said that all their officers and staff that are based at the mission in Afghanistan are accounted for and nobody is missing from duty."
He said that if the person in question is confirmed to be a Pakistani officer, this would be quite a blow to Pakistan.
"There have been cases in the past where retired officers sympathised with the Taliban, and it has not been confirmed whether this is a serving army officer or retired officer."
Fakhar Rehman, a security analyst and senior reporter for Pakistan's AAJ television channel, told Al Jazeera: "So far the Pakistan side have received no confirmed information about this arrest. The identity has yet to be confirmed.
"The military spokesman has no been able to say anything about this arrest. So we are waiting to hear whether Pakistan has been formally informed about this arrest."
Rehman said that Pakistan and Afghanistan had improved relations recently, stating mutual commitments on trade and security.
A battle in Logar province south of Kabul on Friday led to the deaths of two Nato soldiers from the US and five anti-government fighters.
Local security officials said that Afghan air forces, backed by Nato troops, killed 20 Taliban fighters in the northern district of Kunduz, late on Friday.
A car bombing and suicide attacks in the centre of Kabul at the end of February killed at least 16 people. Afghan intelligence officials blamed the attacks on Lashkar-e-Taiba, a Pakistani-based group. It was the deadliest attack in the city since a suicide car bomber killed 17 people outside the Indian embassy in October.
Nato's International Security Assistance Force (Isaf) entered the country following the US invasion in 2001 after the September 11 attacks on the US of the same year.
There are about 90,000 Nato troops in Afghanistan who are slated to begin withdrawing from the country in 2011.
Source: Al Jazeera and agencies