Taipei has accused the Hong Kong government of using a murder case involving two Hongkongers to attempt to degrade the island's sovereignty.
The comment, from Taiwan's Mainland Affairs Council, comes after Taipei said it would not accept the return of murder suspect Chan Tong-kai unless Hong Kong provides it with more evidence of his alleged crime through a mutual legal assistance process.
Chan reportedly confessed to murdering his Hong Kong girlfriend Poon Hiu-wing in Taipei early last year after he had fled back to the SAR. He is expected to be released from prison on Wednesday after serving time for a money laundering offence connected to the killing.
Chan is said to be willing to surrender himself to the Taiwanese authorities after his release.
But Taipei said on Monday that Hong Kong's refusal to provide prosecutors with evidence relating to the case shows it is treating Taiwan as though it is part of China.
The Mainland Affairs Council said it is absolutely impossible for Taiwan to accept such an arrangement and cooperate with Hong Kong.
In response, executive councillor and barrister Ronny Tong said Taiwan's stance on the matter is "total nonsense".
"There is no evidence in Hong Kong which can benefit, or contribute, to the successful prosecution of murder in Taiwan," he said, without elaborating.
The SAR government says Chan cannot be extradited to "any other part of the People's Republic of China", and the murder case was cited by Chief Executive Carrie Lam as the reason for her now abandoned extradition bill, which has sparked months of protests in Hong Kong.