The Chinese embassy in the UK on Sunday refuted the "groundless slanders at China" made by the UK and G7 in their statements on Hong Kong, calling the moves blatant interference in China's internal affairs.

The remarks were made shortly after UK Foreign Secretary Dominic Raab said China's decision to "impose radical changes" to Hong Kong's electoral system was "a further clear breach of the legally binding Sino-British Joint Declaration." The G7 foreign ministers and the high representative of the EU also issued a joint statement on Friday expressing concern over China's decision on Hong Kong's electoral system.

The National People's Congress (NPC), China's top legislature, on Thursday adopted a decision on "improving the electoral system of the HKSAR" after the draft was passed by an overwhelming majority vote at the fourth session of the 13th NPC.

In response to the statements, the embassy spokesperson stressed that the authority of the NPC decision "brooks no challenge" as the decision is made by the country's highest organ of state power and is in line with the provisions of the Constitution of China and the Basic Law of the Hong Kong Special Administrative Region (HKSAR).

"It has a solid political foundation and legal base. Its legitimacy brooks no distortion and its authority allows no challenge," the spokesperson stated.

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The spokesperson said that China has always been committed to "Hong Kong people administering Hong Kong" and ensuring a high degree of autonomy.

By improving the electoral system in the HKSAR and implementing the principle of "patriots governing Hong Kong," Hong Kong will enjoy a more sound development of the democratic system, better safeguard the rights, interests and freedoms of Hong Kong residents and ensure the steady and sustained practice of "One Country, Two Systems," said the spokesperson.

The spokesperson also dismissed Raab's statement on China breaching the Sino-British Joint Declaration, calling it a "non-issue" since the historical mission of the joint declaration "was completed at the handover."

"The Chinese government governs Hong Kong in accordance with the Constitution and the Basic Law, not the Joint Declaration," the spokesperson stressed, adding the core content of the Joint Declaration is to ensure China resumes exercise of sovereignty over Hong Kong.

"The UK has no sovereignty, jurisdiction or right of 'supervision' over Hong Kong after the handover, and it has no so-called 'obligations' to Hong Kong residents. No foreign country or organization has the right to take the Joint Declaration as an excuse to interfere in Hong Kong affairs, which are China's internal affairs," said the spokesperson.

In an interview with CGTN, Victor Gao, chair professor at Soochow University, said the Joint Declaration paves the way for the smooth transfer of sovereignty over Hong Kong. He claimed that the paper has served its purpose for the transfer and is no longer a document with active legal effect.

Hong Kong is under the governance of China's Constitution since its return, Gao noted, "therefore, the NPC has absolute power to make any amendment necessary for the electoral system in Hong Kong."

The professor also appealed to the British government  to "use their wisdom and common sense" to think about the turmoil in Hong Kong in 2019 and 2020.

Regarding democracy in Hong Kong, Gao said the legal system of Hong Kong, as part of China, is under the governance of the NPC, China's top legislature. Therefore, the NPC has solid legal basis to approve decisions related to Hong Kong.

He suggested the British government "see these realities happening on the ground."

"We are confident that Hong Kong as of tomorrow will be of greater stability and people in Hong Kong will develop a greater level of democracy based on the rule of law, the Basic Law. And the 'One Country, Two Systems' will prevail regardless of these false accusations or condemnations by the British government," added Gao.