Dhaka, April 16 -- The firm at the centre of allegations involving parliament's malfunctioning sound system has defended its work, telling investigators that repeated failures stem from "technical errors" such as loose wiring and vibrations caused by lawmakers thumping their desks, rather than financial misconduct.

Zahidur Rahim Joarder, CEO of Communication Technology Limited, offered the explanation on Thursday after being grilled for two hours at the ACC headquarters in Segunbaghicha.

Zahidur defended his firm by pointing to Amanat Enterprise, the company involved in the first phase of the system's renovation.

"The initial part of the reform was done by Amanat Enterprise. Due to their lack of technical experience, we had to step in ...