Taliban militants today attacked an Afghan intelligence service office in the eastern city of Jalalabad, killing at least three people in a bomb and gun assault, officials said.

"The attack was carried out by a vehicle bomb on the Nangarhar provincial NDS office, and then some militants started attacking the office," Ahmad Zia Abdulzai, spokesman for the Nangarhar provincial governor, told AFP.

"Nangarhar NDS (National Directorate of Security) told us at least three of their employees were killed in the attack."

The militants and NDS employees exchanged fire early today.

The head of Nangarhar public hospital told AFP they had received six bodies.

"Six dead bodies and 46 wounded were brought to the hospital -- 26 of them are admitted and the rest were discharged," doctor Najeebullah Kamawal said, adding the injuries were due to flying glass.

Taliban spokesman Zabihullah Mujahid claimed responsibility for the attack in an email statement to the media, claiming several NDS agents were killed in the attack.

The intelligence service has regularly been targeted by the militants.

In December 2012, NDS head Asadullah Khalid was seriously wounded in an attack by a Taliban "envoy" who detonated an explosive device hidden in his underwear.

The militants have stepped up attacks on symbols of power in recent weeks, seeing to destabilise the fragile Afghan state which is in the midst of a political crisis over the appointment of a new president to succeed Hamid Karzai, who has led the country for 13 years.