HONG KONG (REUTERS) - A US congressional panel has warned of an "alarming" rise in China's interference in Hong Kong, noting fears over the city's continued role as a global financial hub.

In its annual report to the Congress on Wednesday (Nov 16), the bipartisan US-China Economic and Security Review Commission highlights the "chilling" abduction and detention of five booksellers based in Hong Kong as well as pressure on media and academic freedoms.

The commission, in a detailed 33-page section on the former British colony, urges a fresh probe from the State Department on Hong Kong's autonomy and freedoms, as well as continued congressional oversight.

"Hong Kong's traditional standing as a global financial hub has significant economic implications for the United States, as US trade and investment ties with Hong Kong are substantial,"the report notes.

Britain handed Hong Kong back to Chinese sovereignty in 1997 under a "one country, two systems" agreement that its freedoms and legal and governmental autonomy would remain intact.

The US report notes that the booksellers' detentions - including two foreign nationals and one who was abducted inside Hong Kong - broadened domestic fears of mainland encroachment and sparked a record turnout in September's legislative election.

"This incident has threatened the maintenance of the 'one country, two systems' framework and led some observers to question Hong Kong's status as a leading global financial hub,"the report warns.

"The election took place against the backdrop of an alarming rise in mainland interference in Hong Kong."

The report comes amid deepening concerns in Beijing over a fledgling independence movement in the city. The High Court this week backed a government demand to bar two recently elected lawmakers, who insulted China when taking their oath of office, from the legislature.

The booksellers were involved in the production and sale of gossipy political titles banned in mainland China but freely available in Hong Kong. Their plight deepened Western governments' concerns about the situation in Hong Kong and sparked formal diplomatic protests.

One of the five men, Swedish passport holder Gui Minhai, who disappeared from the Thai resort of Pattaya last October, is the only one still in detention in China.

Another, Lam Wing Kee, returned to Hong Kong in June, saying he had been held captive by Chinese agents for eight months.

The report places the worsening climate in the city in the context of China's broader disregard for international legal agreements and norms in issues such as the South China Sea and Taiwan.

"China's efforts to exert influence over Hong Kong in ways that undermine Hong Kong's autonomy under the Basic Law reflect a broader pattern of reliance on tools of pressure and coercion ... to advance its interests vis-à-vis its neighbors," the report says.