DAP parliamentary leader Lim Kit Siang has described the Umno supreme council's inability to deduce the identity of 'Malaysian Official 1' as a "mystery".

Lim said this in reference to Umno supreme council member Bung Moktar Radin, who said yesterday 'Malaysian Official 1' was not discussed at the party's supreme council meeting as no one knew who he was.

"This has become the greatest mystery in Malaysian public life today for every Malaysian who regards himself or herself as belonging to 'the informed Malaysian public' would know the identity of 'Malaysian Official 1'," Lim said in a statement today.

The Department of Justice (DOJ) mentioned 'Malaysian Official 1' 36 times in its lawsuit to seize more than US$1 billion in assets purportedly acquired through funds siphoned from 1MDB.

The DOJ had said Malaysian Official 1 received at least US$731 million diverted from 1MDB.

It described Malaysian Official 1 as a senior government official who was the recipient of US$681 million (RM2.6 billion) said to be an Arab donation and is a relative of Riza Aziz, another individual named in the DOJ filing.

Lim said today the cabinet had not discussed the matter despite having met twice since the DOJ announced its lawsuit.

He presumed that this was because they, too, did not know who Malaysian Official 1 was.

Lim urged Putrajaya to rebut the US case if no money had been stolen from 1MDB, as insisted by the government.

"With the information and resources at its command, it should not be difficult for the government to come out with a white paper or a government statement to debunk the 136-page DOJ filing relating to 1MDB, and in the process clear Malaysia’s name and reputation not only as a new member of the Club of Kleptocracy but having become a top kleptocracy in the world," he said.