Security officials inspect the blast site in southwest Pakistan's Quetta, on July 25, 2018. (Xinhua/Stringer)

UNITED NATIONS, July 25 (Xinhua) -- UN Secretary-General Antonio Guterres has condemned Wednesday's suicide attack outside a polling station in Pakistan's Quetta that killed 31 people, said his spokesman.

Guterres extended his heartfelt condolences to the families of the victims and to the government and people of Pakistan, said Stephane Dujarric, the spokesman, in a statement.

The United Nations stands in solidarity with and supports the efforts of the government of Pakistan in the fight against terrorism, said the statement.

The election day attack outside a polling station in Quetta, the capital of Balochistan province in the southwest, killed at least 31 people and injured about 40 others.

In mid-July, a suicide bombing killed 149 people at an election rally in the town of Mastung in the same province. Both attacks were claimed by the Islamic State.