Pro-democracy lawmakers in Hong Kong hit back Friday at former colonial ruler Britain over a report they said showed no "commitment" to the city and strived to avoid embarrassing Beijing.

The British parliamentary report comes as tensions rise over complaints of increasing interference from China in the semi-autonomous city, and Beijing's insistence that it vet candidates for Hong Kong's next leader in 2017.

In a foreword to the report, released Thursday, British Foreign Secretary William Hague said the city's "unique constitutional framework has worked well" and that there was no "perfect model" for electoral reform.

"The important thing is that the people of Hong Kong have a genuine choice and feel that they have a real stake in the outcome," he said.

But pro-democracy lawmakers in Hong Kong condemned the report.

"It contains a lot of waffling without any commitment to help," Civic Party legislator Claudia Mo told AFP.

"I think that the UK government is taking economic considerations much more seriously than political differences."

Britain and China signed trade deals worth more than $24 billion in June, during a visit to London by Chinese Premier Li Keqiang.

- Britain's 'conspicuous silence' -

Concerns are growing that the freedoms Hong Kong was guaranteed under the "one country, two systems" deal when the city was handed back to China by Britain in 1997 are being eroded.

Fears heightened in June when Beijing published a controversial "white paper" on Hong Kong's future, widely seen as a warning to the city not to overstep its bounds.

Hague said that, while "some commentators" had voiced concerns over the threat by the white paper to Hong Kong's autonomy, "I note that both the Central People's Government and the Hong Kong Special Administrative Region Government have been explicit that the paper did not mark a change in policy".

Emily Lau, chairwoman of Hong Kong's Democratic Party, said Britain "should be condemned" after not standing firm against the white paper, the South China Morning Post reported.

"I think the UK owes us a moral obligation to ensure that 'one country, two systems' is effectively implemented," Democratic Party lawmaker Albert Ho told AFP.

Legislators' anger follows heavy criticism from Hong Kong's former number two official, Anson Chan, over Britain's commitment to Hong Kong.

"Britain has been conspicuous by its silence in the wake of the issue of the white paper... The white paper claws back on the provisions of the Joint Declaration (between Britain and China)," she told reporters in Hong Kong earlier this month.

Hong Kong's chief executive is currently chosen by a pro-Beijing committee. While China has promised universal suffrage in 2017, it has ruled out giving voters a say in selecting candidates, prompting fears that only those sympathetic to Beijing will be allowed to stand.

A senior US State Department official said Tuesday that Washington would not take positions on which electoral formula was right for the city, but that it should be "credible".

"We certainly believe that an approach that is judged credible by the people of Hong Kong will extend credibility to the person who is ultimately selected as the chief executive," the official said during a visit to Beijing by US Secretary of State John Kerry.

Hong Kong will announce the results of an official public consultation on electoral reform on Tuesday.

It follows an informal poll last month which saw nearly 800,000 people vote on how the city's next leader should be chosen.

The referendum was followed by a huge pro-democracy march on July 1, which organisers said was attended by more than 500,000 people. Police said 98,600 took part.