Goldman Sachs chief executive David Solomon has made his most forceful defense yet of the Wall Street firm, which is under fire for its dealings with a Malaysian sovereign-wealth fund at the center of an international bribery scandal.

In an message posted to Goldman’s internal website and seen by The Wall Street Journal, Solomon defended the firm’s culture and compliance measures — both of which were criticised by US prosecutors who last month criminally charged two former Goldman bankers in the widening probe of 1Malaysia Development Bhd., known as 1MDB. He had been relatively quiet on the matter so far.