"Mr De Niro checked in by using a different name. . .He seriously doesn't want to be identified," the source was quoted as saying.
The Hollywood iconic star is expected to stay in Malaysia till this weekend.
It is learnt that his visit here is at the invitation of Rosmah Mansor, the Prime Minister's wife, who met him in April during an event in New York.
Rosmah was quoted in a recent report as saying that De Niro had come to the event as a guest "and saw the other side of Malaysia".
Earlier, Rosmah told Sabah's Daily Express that De Niro has accepted her personal invite to come and visit Malaysia.
He had reportedly told Rosmah: "You are very progressive, you are very engaging. I would like to come to your country."
And Rosmah had reportedly responded: "Please come because, otherwise, you would listen to all the wrong things about Malaysia. It is very important to put things in the right perspective."
A Hollywood film industry source said the 66-year-old actor is scheduled to meet the Prime Minister's wife during his stay here.
The versatile actor, director and producer who is best remembered in classics like The Godfather: Part II, 1900, Raging Bull and The Good Shepard.
DS Rosmah ternyata proaktif mempromosikan Malaysia. Semoga Robert De Nero dapat sama-sama berganding tangan dengan Datuk Shah Rukh Khan untuk menaikan imej Malaysia.
Harap-harap selepas ini kita akan sama-sama melihat lebih banyak filem-filem Hollywood akan menjadikan Malaysia sebagai lokasi pengambaran mereka.
Apa pun kita mohon FINAS menapis dahulu filem mereka supaya tidak memaparkan visual Kampung Baru nanti memalukan kaum Melayu.