Rahmatullah Nabil stepped down from the National Directorate of Security (NDS) in December last year after opposing Afghan President Ashraf Ghani’s efforts to improve relations with Pakistan and include Islamabad in peace talks with the Taliban.
Nabil told a group of journalists in Kabul that he had released the documents to provide concrete evidence of Pakistan’s collusion with militants.
The Afghan Taliban insurgency has in the past said it is fighting against the government and Western allies with the support of the Afghan people, and has no need of outside help.
Nabil did not say how the letters had been obtained. Reuters could not independently verify their authenticity.
Since retiring from the intelligence service, Nabil has been strongly critical of Pakistan, which is routinely accused by Afghanistan of sponsoring the Afghan Taliban, a charge it has consistently denied.
VICTIM OF TERRORISM
Authorities in Islamabad have long rejected accusations that Pakistan has provided support and sanctuary for the Afghan Taliban and its leaders, saying it has for years itself been a victim of terrorism, much of it from groups based in Afghanistan.
The release of the documents comes amid worsening tensions between the neighbouring countries in recent weeks, with days of clashes last month during which troops on the border exchanged artillery fire.
It also came days after Pakistan faced heavy criticism in a Congressional Foreign Affairs Committee hearing in Washington.
Afghan President Ghani sharply criticized Pakistan during a visit to a NATO summit in Warsaw last week, and has accused it of conducting an “undeclared war” against Afghanistan.
In response, Islamabad said that Afghanistan was playing a “blame game” instead of cooperating effectively to stop terrorism.