The corruption trial of former Malaysian Prime Minister Najib Razak has entered a second day, with a central bank investigator taking the stand in the case involving the transfer of suspicious money into Najib's bank accounts.

Najib was solemn as he sat in the dock listening to Monday's testimony.

Central bank investigator Azizul Adzani Mohamad Ghafar testified that he secured documents in 2015 related to the bank accounts of Najib, SRC International and another company.

SRC is a former unit of the 1MDB state investment fund, which U.S. investigators say was pilfered of billions by Najib's associates, leading to his election defeat last May.

The trial is the first of several against Najib, who faces 42 graft charges.