The father of suspected Islamic State operative Saifullah, who was killed in an anti-terror operation in Lucknow early on Wednesday, has refused to take the body of a "traitor".

Sartaj, father of Saifullah told reporters, that his son had left home around two and a half months back after being scolded for not working. He said he had hit his son a day before he left home. Saifullah had contacted his family on Monday last week and told them he was going to Saudi Arabia for a job.

"What he has done is not in national interest. We will not the take the dead body of such traitor," Sartaj told reporters.

"A traitor cannot be my son. We are Indians, we were born in India, our forefathers have been born in India. One who works against this country is not my son," he said.

"I used to tell him to find some employment, but he would not listen to me. I used to be angry with him, scolded him many times," he said.

"Around two and a half months back, I slapped him for this. Next day I went to work, when I came back I got to know he has left," he said.

Asked if Saifullah had contacted his family after leaving home, Sartaj said: "He called on last Monday, and said he has got visa to go to Saudi. I said it is your wish," he added.

The suspected Islamic State operative was killed in an anti-terror operation in Lucknow early on Wednesday.

According to police, six pistols of different make, two wireless sets, alarm clocks, steel pipes, an IS flag, two laptops, videos of how to make bombs, four knives, two passports and 600-plus live cartridges were recovered from the site.

His elder brother Khalid said that Saifullah had told the family that he was going to Mumbai to get a visa for Saudi Arabia, where he wanted to go and get some experience in the leather industry.

He had taken the Aadhar card, passport and other papers before leaving three months back, the elder brother told reporters, adding that he did not answer calls thereafter and his mobile phone was usually switched off. He had studied accounts and was a deeply religious youth who offered namaaz five times every day.

Saifullah had rented a room in a five-room house in Haji colony in Thakurganj area of the state capital. He was living there for the past three months along with two other friends, who are now at large, police told media.

The four-year-old house belongs to some Badshah Khan and is looked after by caretaker Abdul Qayyum who lived in the same house with his family.

Qayyum, a madarsa teacher, had fixed the rent at Rs 3,000 after approval from the landlord, the care taker told the police. After police raided the hideout on Tuesday evening, the terror suspect opened fire on the police and refused to surrender despite repeated warnings. Police officials said they tried to neutralize the IS operative and catch him alive but that was not to be.

A National Investigative Agency (NIA) team arrived earlier in the day to take the probe forward. The NIA will look into the items recovered from slain Saifullah's hideout, where he was killed by the Uttar Pradesh Anti Terrorism Squad in an 11-hour-long gunfight.