Pakistan Tehreek-i-Insaf's chief whip in the National Assembly Shireen Mazari on Thursday criticised Chief of Army Staff (COAS) Qamar Bajwa's response to a United States (US) drone strike in Hangu earlier this week.

The Monday night strike killed a Haqqani network commander Abubakar and his partner in the Speen Tal area of Hangu in Khyber Pakhtunkhwa, security sources earlier told DawnNews.

"We don't expect [the] COAS to simply term [the] US Drone strike on Hangu as 'counter-productive'," Mazari said in a tweet on Wednesday.

She also slammed what she called the army chief's "three days of silence" after the drone strike. The army chief's statement, however, came Wednesday night ─ two days after the strike.

"We expect our military to defend our territory against all attacks and intrusions including by US drones on our territory," the PTI leader asserted. "Action, not words, needed," she added.

"[The] COAS [is] expected to act, not just condemn three days after attack," she tweeted.

Inter-Services Public Relations (ISPR) in a statement quoted COAS Bajwa as saying, "Unilateral actions, like drone strike, etc., are counterproductive and against [the] spirit of… ongoing cooperation and intelligence sharing being diligently undertaken by Pakistan."

US drone strikes in Pakistan have been severely criticised by the government in the past.

Following a US drone strike in Balochistan's Dalbandin area which killed Afghan Taliban chief Mullah Akhtar Mansour last year, Prime Minister Nawaz Sharif described the action as a violation of Pakistan's sovereignty.

The US began carrying out drone strikes in 2001, after 9/11, under the administration of then president George W. Bush.

Since then, the US has conducted more than 910 strikes in four countries ─ Afghanistan, Pakistan, Yemen and Somalia. Pakistan is at the top of this list, with at least 424 drone attacks since 2004.

Over 2,500 people have been killed in US drone strikes, of which at least 350 were civilians.