Karachi: A suicide bomber killed at least 128 people on Friday in the worst attack in Pakistan since a 2014 school massacre as the country witnesses a spate of violence ahead of a tense 25 July national election.

More than 120 others were also injured after at an election rally in northwestern Mastung in the restive province of Balochistan, regional officials told Bloomberg News. Interim Balochistan Home Minister Agha Umer Bangalzai confirmed the casualty figures in a post on Twitter. “Suicide bomber loaded with 8 Kg explosives material caused this much devastation," he said.

This is the third major attack to take place that has targeted politicians in the South Asian nation this week. Balochistan Awami Party leader Siraj Raisani was killed in the Mastung blast, while Haroon Bilour, a key leader of the Awami National Party, was murdered in a suicide bombing in the northwestern city of Peshawar. Akram Khan Durrani of the Muttahida Majlis-e-Amal escaped a blast in northern Bannu on Friday.

Beset by widespread violence in previous election campaigns, up until this week Pakistan had been spared from major attacks ahead of the ballot. The armed forces have beefed up security in recent years and Friday’s bombing was the worst in the country since the Pakistani Taliban killed 148 people at an army-run school in the northern city of Peshawar in December 2014.

‘Heinous’ attack

The attack may keep some investors skittish over Pakistan, despite rising foreign investment, spearheaded by China which is providing about $60 billion in funds and loans for infrastructure projects across the country.

The run-up to the poll has also been marred by allegations of widespread army-led media censorship and intimidation. The military, which has directly governed the country for almost half of its independent existence since 1947, has repeatedly denied claims that it is attempting to engineer a controllable government into power.

Pakistan’s army chief General Qamar Javed Bajwa condemned the “heinous" attack in Mashtung, the military’s spokesman Major General Asif Ghafoor said in a Twitter post. “Attempts of inimical forces to derail important democratic activity shall not succeed," he said.

Friday’s explosions coincided with the arrest of former premier Nawaz Sharif and his daughter Maryam as they returned to Pakistan from London after they were handed multi-year jail sentences by an anti-corruption court last week. Key members of the dynastic and former ruling Pakistan Muslim League-Nawaz party, they were detained in Lahore on Friday evening as thousands of supporters greeted their arrival and in some areas clashed with police.

The Sharif’s were convicted after a two-year corruption scandal that engulfed Pakistani politics after the leak of the so-called Panama Papers showed his family used offshore accounts to buy luxury London apartments. The Sharif family has consistently denied any wrong doing and has criticized the judiciary’s handling of his case. Sharif said the nation’s powerful military — which removed him in a 1999 coup — has conspired to manipulate the vote against him.