China has rejected concerns expressed by Britain over Beijing's reinterpretation of Hong Kong's mini-constitution, or "Basic Law."

On Tuesday, the Standing Committee of China's National People's Congress ruled that Beijing has the right to dictate when and how Hong Kong chooses its leaders and lawmakers.

Critics in Hong Kong claimed the ruling contradicted the agreement by which Britain returned Hong Kong to Chinese sovereignty in 1997. Under the so-called "one country, two systems" formula, China promised to leave intact the former British colony's institutions and personal freedoms for at least 50 years.

Britain's Foreign and Commonwealth Office issued a statement saying the ruling appeared to erode the "high degree of autonomy" that was guaranteed to Hong Kong by the Sino-British agreement and the Basic Law.

Chinese Foreign Ministry spokesman Kong Quan rejected the British statement, saying China had acted to preserve Hong Kong's stability.

"Our opinion is very simple and obvious," he said. "The ruling by the standing committee on the Hong Kong Basic Law is very important, and it is beneficial to keep long-term stability in Hong Kong."

In Hong Kong, Qiao Xiaoyang, a senior member of the Chinese parliament, told a public forum that Beijing would not shy away from amending the Basic Law again, if it thought it was necessary.

Beijing's initial decision to interpret the mini-constitution prompted a rowdy demonstration outside the government offices in Hong Kong. There were scuffles and injuries when the police cleared the demonstrators away, and there were scuffles again Tuesday after the NPC announced its ruling on elections.

The NPC ruling reserved the central government's right to veto any attempt by Hong Kong to change the laws that govern elections.

Analysts in Hong Kong say Beijing fears that if allowed to elect their chief executive directly, Hong Kong's voters might choose a leader who would challenge Beijing's authority. Hong Kong's leader is currently selected by a committee appointed by Beijing, and fewer than half of the territory's legislators are directly elected. The next election for chief executive is scheduled for 2007, and pro-democracy activists have been pushing for a direct election the next time around.