The family of Sabeel Ahmed, one of the Indians detained in connection with the failed terror plot in Britain, was questioned by police in Bangalore for the second consecutive day on Friday.

A team led by Deputy Commissioner (Crime) Ravikante Gowda questioned Sabeel's parents -- Zakia Ahmed and Maqbool Ahmed, both retired professors of Bangalore Medical College -- at their residence in Banashankari at around noon.

Zakia and her daughter Fatia, a medical student, were later taken to an undisclosed location and questioned by police and intelligence officials.

They were taken back home with their lawyer, who was present during the questioning.

Gowda did not speak to reporters though police said the family would, if required, be called back for questioning.

Sources said the family of Mohammed Haneef, another doctor from Bangalore detained in Australia in connection with the same terror plot, was not questioned on Friday.

Police Commissioner N Achutha Rao said Sabeel's parents are not sure whether the man who drove the burning jeep into Glasgow airport was their other son Khafeel and are unclear about his involvement with any fundamentalist group.

They said they had a son named Khafeel who had left for Britain, but were unclear about his activities overseas.

They were also unable to confirm whether the driver of the burning vehicle was their son Khafeel, he said.

Rao said the interrogation largely focussed on the family's background, the education of their sons and their activities.

Haneef's family said it was touched by Prime Minister Manmohan Singh's [Images] concern for the agony of the mothers of the detained persons.

Haneef's younger brother Sohaib said he was hopeful he would return safely with his "honour intact."

"We appreciate the prime minister's reaction to our pain. It only shows how sensitive he is to the concerns of the people," Haneef's father-in-law Ashwaq Ahmed said while reacting to the prime minister's statement that he was unable to sleep after seeing the pain of the mothers.

Ashwaq said the family also appreciated the prime minister's statement to avoid labelling persons of any particular nationality as terrorists.

Ashwaq and Sohaib maintained that Haneef is innocent. Despite the decision of Australian authorities to extend Haneef's detention by four days, Sohaib said, "We are hopeful that he will return with all his honour and dignity intact."

Asked whether police were probing the involvement of the suspects in any local religious network or groups like the outlawed Students Islamic Movement of India, Police Commissioner Rao said the interrogation had included all these aspects.

"We are probing all possible angles in the case," he said.

"We are in the process of finding out all about their activities while they were studying in Bangalore, whether any kind of indoctrination had taken place here, whether they were involved in any groups here," Rao added.

Rao said no "incriminating" evidence had been found so far.

Sabeel's family said he, Haneef and Khafeel were related. Khafeel completed his BE in mechanical engineering from University BDT College of Engineering at Davangere and was in the 1996-2000 batch.

He left for Britain after one year of his MPhil and completed his PhD in aerodynamics. College sources said Khafeel was a quiet person with a good record who took part in cultural and sports activities.