The attack in Quetta, the capital of Baluchistan province, came a day after a Taleban suicide bomber killed 30 people at a police funeral in the city.
It came the same day as the US has warned Americans not to travel to Pakistan and evacuated most government personnel from the country’s second-largest city because of a threat to its consulate.
Pakistan has experienced a rash of deadly attacks since prime minister Nawaz Sharif took office at the beginning of June, sparking criticism that the government does not have a coherent plan to fight the growing problem of violent extremism in the country.
The former provincial minister who was attacked yesterday, Ali Madad Jatak, escaped unharmed, said police officer Bashir Ahmad Barohi. However, six people were killed and 15 wounded, he said.
The attack took place when Mr Jatak and a group of his supporters were leaving a mosque after sunrise prayers marking the start of the Muslim holiday of Eid al-Fitr at the end of the holy month of Ramadan, said Mr Barohi.
Baluchistan is home to both Islamic militants and separatists who have been waging a low-level insurgency against the government for decades.
Suspected separatists killed 13 people they pulled off a bus in Baluchistan earlier this week, as well as a paramilitary soldier who tried to stop them.
Also yesterday, guards at a Shiite mosque on the outskirts of the capital, Islamabad, shot and killed a would-be suicide bomber before he could set off his explosives, police officer Abid Hussain said.
The attacker opened fire on the guards, wounding three of them before he was killed, said Mr Hussain.
One of the injured guards died on way to hospital, another police officer, Mohammed Riaz, said.
US consulates have been attacked in different parts of Pakistan, and Washington is still scarred by the memory of the attack last year on a diplomatic post in Benghazi, Libya, that killed US ambassador Chris Stevens and three other Americans.
The US said it was shifting non-essential staff from the eastern Pakistani city of Lahore to the capital, Islamabad, after a specific threat to the consulate there, said US embassy spokeswoman Meghan Gregonis.
Emergency personnel will stay in Lahore, and embassy officials do not know when the consulate will re-open, she said.
“We received information regarding a threat to the consulate,” said Ms Gregonis. “As a precautionary measure, we are undertaking a drawdown of all except emergency personnel.”
Meanwhile, British officials are closely monitoring the security situation in Pakistan.
“We’re aware of US actions, and remain in close contact with US authorities,” a spokeswoman said. “Security of our staff is an over-riding priority. We keep security measures and travel advice under constant review.”
Britain followed the US in evacuating embassy staff from Yemen earlier this week, in response to a separate threat which led Washington to temporarily close down 19 diplomatic posts in the Middle East and North Africa.
No timescale has yet been set for the return of the British ambassador or her staff to Sana’a.