Police among dead
Liaqat Ali Khan, the police chief in Peshawar, told the AFP that two policemen were among the dead, but he did not give details.
Malik Jehangir, who was in charge of the checkpoint, said policemen were checking vehicles when he saw a suspicious black car across the barrier and asked one of the officers to check it.
"I saw that there was some argument between the driver and the policeman and suddenly a blast downed me with shrapnel piercing my shoulder," he said.
Another witness, Akbar Ali, said that he was riding a motorcycle and waiting in the queue at the checkpoint when he saw a scuffle between the bomber and the policeman.
Officials say the death toll is likely to rise.
Anti-government Taliban fighters have struck numerous times in Pakistan in recent weeks, killing more than 300 civilians and soldiers.
The attacks appear to be aimed at weakening the government's resolve to continue its military operation in South Waziristan, the Taliban's main bastion, on the border with Afghanistan.
Last month, a car bomb ripped through a crowded grocery market in the centre of Peshawar, killing more than 100 people, mainly women and children.
The Taliban said it did not carry out the October attack in Peshawar that was described as the deadliest in the country in two years.
A truck bombing at the regional headquarters of Pakistan's national intelligence agency killed at least 10 people in Peshawar on Friday.
Meanwhile, Pakistan's army claims they are making good progress.