ISLAMABAD: Foreign Secretary Aizaz Ahmad Chaudhry on Thursday said the Indian intelligence agency Research and Analysis Wing (RAW) is involved in various terrorist activities across Pakistan.

Chaudhry added that the matter had been taken up "a number of times" at the highest level with India through diplomatic channels.

He also touched upon the Karachi bus attack in an informal conversation with media representatives in Islamabad, saying that it is too early to confirm the involvement of Daesh.

Read: 43 killed in attack on bus carrying Ismailis in Karachi

Chaudhry said that Daesh's involvement in the attack cannot be established on the basis of a pamphlet purportedly left by militant group. However, he said, security agencies are investigating the attack.

A letter was left by the gunmen on Wednesday who attacked the bus carrying members of the Ismaili community.

Khorasan province, a division of the self-styled Islamic State (IS) in the Afghan-Pakistan region, claimed the deadly attack on the bus. In a message on Twitter, the group said 43 “apostates” were killed and more than 30 wounded in the attack. It did not give details of the attack.

In response to a question, the foreign secretary said that Pakistan is fighting a war on terror and this war is yet to be over.

He said Pakistan is a responsible nuclear state and has proven that it has used its nuclear technology for socio-economic and scientific development.

Earlier during the day, the spokesperson for the Foreign Office responding to a question about Pakistan's relationship with Afghanistan had said that Pakistan has told Afghanistan that Indian spy agency RAW should not be allowed to operate against Pakistan from Afghan territory.

The statement follows after a visit by Pakistani premier Nawaz Sharif to Afghanistan, where he pledged Pakistan's support in the fight against the Afghan Taliban.

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Last week, the military’s top brass accused RAW of supporting terrorism in Pakistan. A previous ISPR statement on a meeting of the Corps Com­manders held at the General Headquarters said: “The conference also took serious notice of RAW’s involvement in whipping up terrorism in Pakistan.”

While RAW has been blamed by Pakistani authorities in the past, it is unusual for a corps commanders’ conference to directly point fingers at the hostile intelligence outfit.

Know more: RAW instigating terrorism, says army

Despite consistently pointing out RAW’s hand behind terrorism in the country, Pakistani authorities have traditionally been uncommunicative about proofs. Indian backing of insurgency in Balochistan got a mention in a Pakistan-India joint statement issued after a meeting of their prime ministers in Sharm-el-Sheikh in 2009, but Islama­bad failed to follow up that diplomatic achievement with concrete proofs.

Earlier this year, however, the government decided to take a tougher approach towards India and forcefully raise its concerns over alleged Indian involvement in acts of terrorism in the country. The change had been forced by Delhi’s continued terrorism allegations for building a narrative that India was a victim of Pakistan-sponsored terrorism.