A deadly attack on an Afghan army outpost killing 21 soldiers was planned 'outside Afghanistan'.
The 'outside Afghanistan' term used by Afghan officials was made to refer to neighbouring Pakistan.
Hundreds of militants stormed an Afghan army outpost in the eastern province of Kunar on Sunday, triggering a four-hour battle.
According to Dawn News, the attack is the single deadliest attack on Afghan troops in recent months by the insurgents and also left five soldiers missing.
The Taliban has claimed responsibility for the attack.
Defence ministry spokesman General Zahir Azimi said it was a very big attack planned outside Afghanistan.
He added that Afghanistan has human and electronic intelligence evidence showing that hundreds of fighters, including Pakistanis, Arabs and Chechens in addition to local insurgents, had come from the other side of the border.