Executive Council member and New People's Party chairwoman Regina Ip says the government is still working on laws that will impose quarantine on people coming from the mainland, just hours before the measure is due to take effect.

The former security minister said the fact that government lawyers were still drafting the legislation on Friday morning when it is due to take effect at midnight is a sign that the government has failed in its emergency planning.

"The government officials are working extremely hard, but they should have acted earlier with greater foresight, you know," she told RTHK's Hugh Chiverton.

"They should have the whole plan, all the necessary regulation right at the start. They should have such emergency plans ready, a whole package ready," she said.

"Actually, even in times where there's no outbreak, the government should have such emergency plans which they have whenever there is a need."

The administration has said that anyone entering Hong Kong from the mainland, or who enters from elsewhere having visited the mainland in the past 14 days, will be subject to mandatory quarantine for two weeks.

Ip said there was a need for the quarantine laws to be set out in detail and gazetted before they took effect. She expected the government to make a further announcement later on Friday.