A high-ranking official said Tuesday that Tokyo hopes Hong Kong's "free and open regime will be maintained," indirectly urging authorities there to seek a peaceful solution to the ongoing street protests calling for universal suffrage for local residents.

"The future of Hong Kong is a big matter of concern for us. We believe Hong Kong's democratic prosperity and stability will play a big role in the Asia-Pacific region," Deputy Chief Cabinet Secretary Hiroshige Seko said during a daily press briefing at the prime minister's office.

"Japan hopes the free and open regime will be maintained, as it has in the past, under the 'one-country, two-systems' formula," he said.

Seko stopped short of saying whether Tokyo supports the protesters' campaign. When pressed, he simply repeated the hope that Hong Kong will continue to be free and open.

Seko's choice of words appeared to reflect concern that Beijing might seize on his comments as evidence of interference in the domestic affairs of a sovereign country.

Meanwhile on Monday the United States reportedly expressed its support for universal suffrage in Hong Kong and urged both sides to exercise restraint.

"The United States supports universal suffrage in Hong Kong in accordance with the Basic Law and we support the aspirations of the Hong Kong people," White House spokesman Josh Earnest was quoted as telling reporters. "We have consistently made our position known to Beijing and will continue to do so."