KABUL: A bomb blast on a minibus killed at least seven people in the western Afghan city of Herat on Saturday, officials told AFP. 

The sticky bomb was attached to the fuel tank of the bus, and left nine other people wounded. 

"Four women were among the seven killed," the head of Herat's provincial hospital, Arif Jalali said. 

The blast was confirmed by Herat's intelligence office. 

"Initial reports indicate it was a sticky bomb attached to the fuel tank of the passenger vehicle," said Sabit Harwi, a spokesman for the office. 

Herat provincial police also confirmed the bomb blast. 

Security in Afghanistan has vastly improved since a two-decade long insurgency by the Taliban ended with the group's capture of the capital Kabul in August. 

However, several attacks are reported each week throughout the country, including some claimed by the regional chapter of the Daesh militant group. 

Herat is the country's third-biggest city, close to the border with Iran, and has remained relatively peaceful in recent months.