The Hong Kong and Macao Affairs Office of the State Council said on Tuesday it will never allow any illegal manipulation in the Legislative Council election in the Hong Kong Special Administrative Region.

The office slammed a so-called LegCo primary election held by the opposition camp over the weekend in a statement, saying the acts posed a blatant challenge to the HKSAR Basic Law and the national security law for the HKSAR.

The office said it supports relevant authorities to investigate and punish the illegal acts in accordance with the law.

Anti-China forces and opposition political groups organized the so-called primary election, using the "poll" as a pretext to coordinate campaigns for opposition candidates before the LegCo candidate nomination period starts, according to the statement.

The acts posed a serious challenge to the constitutional order of the HKSAR, undermined its democratic electoral system, and eroded the power of the HKSAR government to organize elections, the office's representative said in the statement.

Elections are an important manifestation of the exercise of political and democratic rights by residents. They must be conducted in accordance with the law and the procedures provided for by it, and conform to the principles of openness, fairness and justice, the representative said.

Neither the Basic Law nor the current electoral laws of the HKSAR provide for the system of "primary election" or "poll". It is illegal for any group or individual to organize such elections, which don't have legal effect or constitutional basis, the representative said.

"The so-called primary election has misled voters about their voting preferences in legal elections and thus led to unfair elections," the representative added.

Organizing such activities also allegedly violates some regulations by organizing a gathering under the situation of COVID-19 prevention and control, and obtaining large amounts of personal information and voter data, according to the office.

The HKSAR government has received a large number of complaints and should investigate and punish those responsible in accordance with the law, it said.

The representative said the main organizers of the activities are advocates of "Hong Kong independence" and political agents of foreign forces in Hong Kong.

"They have a clear political purpose, which is to overthrow the Hong Kong SAR government and seize governance," the representative said, "They want to make Hong Kong a base for infiltration and subversion against the country under so-called public opinion".

The representative said that with the enactment and implementation of the national security law, Hong Kong is ushering in a new turning point from chaos to governance and back to the right track.

The representative called on people in Hong Kong to resist any attempt to challenge the bottom line of the "one country, two systems" principal and undermine Hong Kong's prosperity and stability, and fully support the implementation of the national security law in Hong Kong.