Unions in Hong Kong have faced heightened scrutiny since Beijing imposed a sweeping national security law on the city in 2020, following huge and often violent pro-democracy protests the year before.

Dozens of trade unions, including the top teacher's union and largest pro-democracy labour coalition, have disbanded and collective actions such as strikes are rare.

The government said the official in charge of union registrations should have more powers "to better fulfil the duty of safeguarding national security".

Under the proposed rules, unions must get the registrar's approval before accepting funds from "external forces" -- a broad label that applies to non-Chinese governments, political groups and international organisations.

The funds could not be used for local elections.

The registrar would also have the power to reject union applications on national security grounds, with the decision not subject to appeal.

"The registrar must regard national security as the most important factor," the government said.

The proposal will be sent to Hong Kong's opposition-free legislature in April.

Hong Kong has arrested 318 people and convicted 161 under its two national security laws as of the start of this month.

The government said on Wednesday that people convicted of national security crimes should be permanently barred from serving as union officers and promoters.

The proposals also made it harder for Hong Kong labour unions and their members to join international groups.

The registrar should also be allowed to enter any union-occupied premises to inspect records, conduct examinations and seize evidence, the government said.

The Hong Kong Labour Rights Monitor, a UK-based advocacy group, called the proposals a "serious infringement of workers' rights" and said unions would be "subject to strict political surveillance."

"The government is deliberately using national security needs as a pretext to suppress dissent," the group said in a statement.

Hong Kong had just over 1,400 registered trade unions at the end of last year, official figures show.