If passed, the amendment will allow case-by-case fugitive transfers with jurisdictions Hong Kong does not have a deal with, including Taiwan and the mainland.

But in a letter to the Security Bureau dated April 30, Legco’s legal adviser raised dozens of questions about the proposal, including whether the government had changed its policy on seeking a formal extradition agreement with the mainland.

The letter said that the intent of excluding China from the Fugitive Offenders Ordinance when the law was localised for the handover in 1997 was to have a separate agreement with the mainland.

Timothy Tso Chi-yuen, the division’s senior assistant legal adviser, said the bureau should explain if there had been a policy change, and if so, give the reasons.

Tso also wrote that there had long been a case-by-case arrangement under the existing ordinance, to allow Hong Kong to transfer fugitives to places it lacked an extradition deal with.

Such a move was possible if the chief executive issued an order under the ordinance, he wrote.

Tso urged the bureau to clarify why such an arrangement was considered “impracticable” now.

His other queries included whether further human rights safeguards could be introduced to the bill, as well as how Legco and the public would be informed of possible transfer requests.

By convention, the bureau had to answer questions from the division, lawmakers said.

Separately, in an online commentary, University of Hong Kong legal scholar Chen said local officials should give “serious consideration” to retaining the right to refuse to hand over Hongkongers to the mainland. Instead, the government could consider trying residents locally for crimes committed across the border.

Chen said it was advisable to include more restrictions and safeguards in the bill. He said case-by-case extradition should be limited to “the most heinous crimes” and a small number of the “most serious offences”.

The professor also said the amendment should be non-retroactive, meaning it would only apply to cases that happened after the bill passed.

He also said that if the bill passed, “Hong Kong courts will be placed in a difficult and invidious position”, as judges would have to decide whether the mainland’s legal system complied with human rights standards before granting extradition requests.

In a statement issued on Friday night, the Security Bureau said the exclusion of mainland China from the existing Fugitive Offenders Ordinance was not intentional.

A bureau spokesman said mainland China was not included as a destination of fugitive transfer in the British law the ordinance was based on.

“The matter was not handled in the process of localising the ordinance, and the exclusion of China was not intentional,” he said.

The spokesman also said the current amendment did not target individual jurisdictions, but any that currently lacks an extradition agreement with Hong Kong.

The bureau will issue a reply and submit it to the bills committee before May 14, he said.

Civic Party lawmaker Dennis Kwok said Tso had pointed out the flaws and unanswered questions related to the bill, noting that the document had been in greater detail than usual.

“Why is there a sudden change in a policy that was established 20 years ago to exclude the mainland?” Kwok said.

Pro-establishment legislator Regina Ip Lau Suk-yee, a former security minister, said the existing case-by-case arrangement would not work in Chan’s case, as Taiwan was considered by the central government as part of China.

Two functional constituency lawmakers in Ip’s camp – Ma Fung-kwok and Tony Tse Wai-chuen – also faced pressure from their sectors to properly consult electors before backing the bill.

Meanwhile, a delegation led by pro-democracy veteran Martin Lee Chu-ming will head to Canada and the United States on a 14-day visit in a bid to persuade the international community to voice its opposition to the bill.

The group will also testify at a public hearing of the US Congressional-Executive Commission on China in Washington to voice concerns over the threats Hongkongers may face from the bill.

Additional reporting by Alvin Lum