"We hope that the upcoming consultation period will produce arrangements which allow a meaningful advance for democracy in Hong Kong," the Foreign Office said in a statement.
"The British government is concerned about the situation," it said.
Referring to the right to demonstrate, the Foreign Office said: "It is important for Hong Kong to preserve these rights and for Hong Kong people to exercise them within the law".
The Foreign Office referred to the Sino-British Joint Declaration, which enshrines the "one country, two systems" principle and preserves Hong Kong's previous capitalist system and way of life for a period up to 2047.
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Thousands of defiant protesters stood their ground today after facing tear gas and riot police in overnight clashes.
In the worst unrest since the former British colony was handed back to China in 1997, demonstrators fought hours of running battles with police.
The demonstrators have demanded full universal suffrage after Beijing last month said it would allow elections for the semi-autonomous city's next leader in 2017 but would vet the candidates -- a decision branded a "fake democracy".