Mr Attarzadeh was the commercial attache at Iran's consulate in Peshawar
An Iranian diplomat taken hostage in Pakistan in 2008 has been freed and returned to Iran, according to Iranian diplomatic sources.
Gunmen seized Heshmatollah Attarzadeh as he drove to work at the Iranian consulate in Pakistan's north-western city of Peshawar in November 2008.
Mr Attarzadeh was the commercial attache at the consulate.
His abduction came amid a surge of violence in the region and a wave of attacks blamed on Islamist militants.
"He has been freed," Abbas Ali Abdullahi, head of the Iranian consulate in Peshawar, was quoted as telling Reuters news agency. "It's confirmed that he has reached Iran."
Mr Abdullahi gave no further details of how Mr Attarzadeh's freedom was secured.
The Iranian News Network Channel (IRINN) reported that Iranian agents had freed Mr Attarzadeh "in a complicated intelligence operation" and returned him safely to Iran.
There has been no official Pakistani comment on the incident.
Mr Attarzadeh was seized and his guard killed after gunmen sprayed the car in which they travelling with bullets.
The diplomat's car was hit by bullets before he was abducted
Iran's foreign ministry condemned the kidnapping as "a terrorist act" and summoned Pakistan's ambassador to discuss the incident.
The abduction came during a wave of attacks and abductions of foreign workers in the area, close to Pakistan's lawless tribal areas.
Areas close to Peshawar - the biggest city in north-west Pakistan - are known to be Taliban and al-Qaeda strongholds.
Last November, a Pakistani who worked at Iran's Peshawar consulate was shot dead at his home in the city.
Correspondents say that Iranian diplomats and nationals have been targeted in predominantly Sunni Pakistan since the 1990s amid Shia-Sunni sectarian tensions.
Bilateral relations have been strained since predominantly Shia-Iran said Pakistan-based agents were involved in a suicide bombing in south-east Iran last October which killed 42 people.
The attack was blamed on the Sunni resistance group, Jundullah.
Last month, Iranian authorities arrested Jundullah's leader, Abdolmalek Rigi and are reportedly holding him in eastern Iran.