BEIJING (Reuters) - China has expressed "strong dissatisfaction" with the G7 declaration on Hong Kong calling for averting violence in the semi-autonomous city, more than two months after demonstrations against the pro-Beijing government.

Foreign Ministry spokesman Geng Shuang reiterated to the press that the situation in the former British colony is China's internal affair and "no country, organization or person has the right to interfere."

China requires the G7 members to "stop hiding bad intentions, interfere in others' affairs and secretly prepare for illegal activities," Ging said.

In its final declaration after a three-day summit in Biarritz, France, the Group of Eight industrialized nations reaffirmed "the importance of the 1984 Sino-British Declaration on Hong Kong" and called for "avoiding violence."

The 1984 Declaration, which preceded Hong Kong's return to China in 1997 for 50 years, guaranteed the city's autonomy under the principle of "one country, two systems".

Ging said the 1984 declaration "confirms that China will regain sovereignty over Hong Kong," which was first given to London in the 19th century.

Hong Kong leader Kari Lam said on Tuesday that more violence in three months of anti-government protests had become more serious.

Protests escalated in June over an ongoing pending bill that would have allowed extradition to the Chinese mainland - facing Hong Kong provinces - for trial.

Over the past 12 weeks, the protests have evolved into widespread demands for greater democracy under the "One Country, Two Systems" principle, an arrangement that has secured much autonomy for Hong Kong since Britain returned it to Chinese rule in 1997.