The foreign ministers of the G7 group said Hong Kong's vetting process for Sunday's vote undermined Hong Kong's high degree of autonomy under the "One Country, Two Systems" principle.
World powers have condemned Hong's Kong tightly vetted legislature vote, saying rules imposed by Beijing that reduced directly elected seats and controlled who could stand had eroded democracy in the Chinese territory.
The foreign ministers of the G7 group of most developed nations expressed on Monday "grave concern over the erosion of democratic elements" in Hong Kong's electoral system after Sunday's poll.
Canada, France, Germany, Italy, Japan, the UK and US called on China "to restore confidence in Hong Kong's political institutions and end the unwarranted oppression of those who promote democratic values and the defence of rights and freedoms".
The new vetting process "to severely restrict the choice of candidates on the ballot paper undermined Hong Kong's high degree of autonomy" under the principle of "One Country, Two Systems" agreed for the handover of the territory from the UK to China in 1997.
The European Union's foreign policy chief Josep Borrell said in a statement that the poll was "yet another step in the dismantling of the ‘One Country Two Systems’ principle," and called for a "high degree of autonomy as well as respect for human rights and fundamental freedoms, democratic principles and the rule of law" in Hong Kong.
In an earlier statement, Britain, the United States, Canada, Australia and New Zealand had rebuked the new system, saying "these changes eliminated any meaningful political opposition".
Low turnout for first vote under new order
China imposed a national security law in the former British colony that criminalised much dissent and introduced political rules that vet the loyalty of anyone standing for office.
The first public vote under this new order was held on Sunday for the city's legislature, with a historic low turnout recorded and the number of those directly elected slashed from half to 22 percent.
Figures showed just 30 percent of the electorate cast ballots, the lowest rate both of the period since the city's 1997 handover to China and the British colonial era.
Turnout at the last legislature polls in 2016 was 58 percent, while the 2019 district council elections, when anti-Beijing figures won a landslide, saw a record 71 percent.
Hong Kong's chief executive Carrie Lam defended the new system and brushed off the low turnout.
Zhao Lijian, China's foreign ministry spokesperson, blamed the low turnout on the pandemic and "anti-China elements bent on destroying Hong Kong and the interference of external forces".