KARACHI: In a startling addition to the ambulance controversyin connection with the Panama Papers case, Pakistan Tehreek-i-Insaf (PTI) leader Naeemul Haq on Thursday accused the Intelligence Bureau (IB) of spying on the Joint Investigation Team (JIT) during the interrogation of Hussain Nawaz, son of deposed prime minister Nawaz Sharif.

Earlier in May, the arrival of an ambulance from the Pakistan Institute of Medical Sciences (Pims) at the Federal Judicial Academy (FJA) while the investigation was under way fanned rumours on electronic and social media about some JIT member`s health. Some TV channels also ran unconfirmed stories that Mr Hussain Nawaz had got sick.

The ambulance was stopped at the gate but allowed to enter after it was clarified that it had been called by the FJA`s management.

Referring to the incident, Mr Haq told reporters on Thursday that the ambulance was sent with surveillance equipment to spy on the JIT.

`Confirmed: The ambulance sent to JIT during its interrogation of Sharif family was in fact an IB vehicle sent to monitor inside events,` the PTI leader tweeted on his official account [@naeemul_haque].

However, he did not disclose from where he got the information.

He claimed he had learned through reliable sources that the government intended to appoint IB chief Aftab Sultan as next chairman of the National Accountability Bureau (NAB).

A few days ago, PTI chairman Imran Khan demanded the IB chief resign for visiting Nawaz Sharif in London. He alleged that Mr Sultan had visited London to offer `protocol` to the ousted prime minister and his family.

`IB head must resign immediately. What was he doing visiting a disqualified PM in London over 4 days at taxpayer expense?` he said in his first of the many tweets.