The president and executive director said that 1MDB had already responded to Pua's allegations through 48 easily obtainable press announcements since January this year.
Pua released a statement on Friday asking Arul to prove his claim that 1MDB was an "open book" and to answer whether the state investment fund transferred nearly US$1.2bil to Gold Star Limited, a company controlled by businessman Jho Low.
"In addition, the Auditor-General has presented an interim report answering many of the questions raised, in early July 2015 to the Public Accounts Committee (of which YB Tony Pua is a member)," said Arul in a press statement on Friday.
"YB Tony Pua is no doubt aware that 1MDB is the most-investigated company in Malaysia," said Arul.
"We have shared and will continue to share, all relevant information to the lawful investigating authorities," he said.
He said these included Bank Negara Malaysia, the Malaysian Anti-Corruption Commission, the police, the Attorney-General's Chambers, the Auditor-General and the PAC.
"These independent, thorough and professional investigations are the appropriate forum to determine the truth about 1MDB," said Arul.
"A trial by certain media or by certain Opposition politicians, outside of due process and the requirements of the law, will not benefit anyone.
"1MDB is very much focused on the implementation of our rationalisation plan, which is going full steam ahead despite the recycled allegations of YB Tony Pua," he said.
Arul said that he was committed to stabilising the company and meeting their debt obligations.
He said that he was also focused on delivering strategic projects of "national importance", such as the Tun Razak Exchange (TRX), Bandar Malaysia and Edra Energy Berhad.