Supporting 1MDB-linked businessperson Jho Low is akin to betraying the country and Umno, an Umno veteran was cited as saying by Sinar Harian.
Umno Veterans Club secretary Mustapha Yaakub said a sane party leader would instead want action to be taken against Low, whom he said was responsible for the 1MDB scandal.
"An Umno leader who is sane will not support Low, what more love that penyangak (scoundrel).
"In fact, they would want to see action taken against Low if it is true that he was involved in stealing 1MDB funds," Mustapha was quoted as saying by the Malay daily.
Previously, other former Umno leaders Rais Yatim and Rafidah Aziz had spoken out against Low.
Both were critical of Communications and Multimedia Minister Salleh Said Keruak, who had commented that reports of a superyacht seized by Indonesian authorities being linked to 1MDB and Low were fake news.
This is in reference to the Equanimity, which Low is alleged to have purchased with US$250 million allegedly misappropriated from 1MDB.
The 1MDB scandal is being investigated in multiple jurisdictions and has been described by US attorney-general Jeff Sessions as "kleptocracy at its worst".
US authorities believe that at least US$4.5 billion in 1MDB funds was misappropriated and allegedly laundered through the financial system in the US and other countries.
The country's Department of Justice (DOJ) is seeking to seize US$1.7 billion in assets allegedly acquired using the stolen money.
1MDB has denied any misappropriation of its funds.