Serial killer Ivan Milat remains in hospital almost a week after he was transferred from a Sydney prison.

The notorious murderer was transferred from Long Bay jail to Prince of Wales Hospital in Randwick on Friday, August 9.

Milat was found guilty in 1996 of murdering seven backpackers whose bodies were found in makeshift graves in Belanglo State Forest in the 1990s.

Corrective Services on Thursday confirmed Milat was still in a secure annexe at the hospital but was unable to give an update on his condition.

The 74-year-old spent two weeks at Prince of Wales Hospital in May when he was diagnosed with oesophagus and stomach cancer.