A special team drafted to probe the alleged links of some city doctors in the UK terror plot has stepped up investigations but nothing 'suspicious' has been found so far, a senior police official said on Saturday.

"We require at least 15 days to three weeks to complete the investigations," Joint Commissioner of Police (Crime), Gopal B Hosur told PTI.

The team subjected parents of Dr Sabeel Ahmed and Kafeel Ahmed to questioning on Friday.

"So far we have not found anything suspicious," he said.

The police team led by Deputy Commissioner of Police B R Ravikanthe Gowda interrogated Sabeel's parents.

Hosur also questioned them at an undisclosed place.

When asked whether Maqbool Ahmed and Zakia Ahmed, parents of Sabeel, would be questioned again, Hosur said, 'we are yet to decide but if need be, it will be done'.

Sources said the police team has been gathering information also about the antecedents of Dr Mohammed Haneef, who was arrested in Australia.