By Abhijith Ganapavaram

NEW DELHI, Oct 7 (Reuters) - India's civil aviation

minister denied on Tuesday there was any "manipulation" in an

official investigation into the crash of an Air India Dreamliner

in June, after the father of the flight's captain complained

about the actions of investigators.

It was the first official reaction to a complaint by Pushkar

Raj Sabharwal sent to a pilots' union last month in which he

said investigators had visited his home and implied that his son

had cut the fuel to the plane's engines after takeoff.

Sabharwal, 91, emailed the Federation of Indian Pilots (FIP)

to complain of "selective" releases of information from the

investigators that had led to speculation about the actions of

his late son, Captain Sumeet Sabharwal.

"There is no manipulation or there is no dirty business

happening in the investigation," Civil Aviation Minister Ram

Mohan Naidu told broadcaster India Today.

"It is a very clean and very thorough process that we are

following according to the rules that have been set up, so we

are going to ensure that commitment is maintained," he said in

an interview, when asked if he had any assurances for Sabharwal.

Air India flight 171 crashed moments after it took off from

Ahmedabad in June, killing 260 people.

A preliminary investigation report by Aircraft Accident

Investigation Bureau (AAIB) showed the plane's fuel engine

switches had almost simultaneously flipped from run to cutoff

just after takeoff.

A source briefed on U.S. officials' early assessment of

evidence in July told Reuters the cockpit recording of dialogue

between the two pilots supported the view that Captain Sabharwal

had cut the flow of fuel to the engines.

Pushkar Raj Sabharwal and the FIP did not immediately

respond to emails seeking comment.

Sabharwal wrote a separate letter to the ministry in August,

in which he requested India's government open an additional

investigation into the deadly crash. Meanwhile, India's Supreme

Court asked the government to respond to a plea seeking an

independent investigation into the crash.

Reuters reported on Tuesday that India has sought more

information from Boeing ( BA ) after an emergency power system

unexpectedly activated on a separate Air India 787 Dreamliner on

Saturday.