Amrullah Saleh following an interview with Tolo News said at least 4000 Afghan national security forces were also injured during the past three months.
He said the increase in militants attacks is the main reason behind Afghan security forces growing casualties during the recent months.
In the meantime a spokesman for Afghan presidential palace Aimal Faizi confirmed the growing casualties of Afghan national security forces however he denied that 1800 Afghan national security forces were killed during the past three months.
This comes as Afghan president Hamid Karzai recently following a session in Afghan house of representatives said at least 20 Afghan security forces are being killed in every 24 hours across the country.
Afghan presidential palace spokesman Aimal Faizi expressed concerns regarding the growing casualties of Afghan security forces.
According to Afghan officials majority of the Afghan security forces are suffering due to roadside improvised explosive device attacks.
Former Afghan NDS chief Amrullah Saleh during his interview with Tolo News also said the Afghan government was facing civil war in a number of provinces of Afghanistan.
He said Afghan government resources are not properly used to strenghthen the government and there are individuals inside the Afghan government who are misusing the national resources and there are certain groups in Afghaistan who are opposing each other which weakens the Afghan government and in other words are triggering civil war in Afghanistan.