TOKYO (REUTERS) - Japan is "seriously concerned" about the move by China's Parliament to go forward with national security legislation for Hong Kong that observers fear could endanger its special autonomy and freedoms, the foreign ministry said on Thursday (May 28).

In a rare statement issued minutes after the security Bill was approved, Japan also called Hong Kong an "extremely important partner", underscoring close economic ties and people-to-people exchanges.

"Japan is seriously concerned about the (Chinese Parliament's) decision," the ministry statement said.

"It is the long-standing policy of Japan to attach great importance to upholding a free and open system which Hong Kong has been enjoying and the democratic and stable development of Hong Kong under the 'one country, two system' framework."

The Chinese government's security law for the city is fuelling fears that Beijing is imposing its authority and eroding the high degree of autonomy the former British colony has enjoyed under the "one country, two systems'' formula since it returned to Chinese rule in 1997.

China says the legislation is aimed at tackling secession, subversion, terrorism and foreign interference in the city but the plan, unveiled in Beijing last week, has triggered the first big protests in Hong Kong for months.

Tokyo said it has conveyed its views to Beijing and that it will carefully observe further developments in Hong Kong.