Britain must push to see genuine democracy introduced in its former colony Hong Kong, whatever China says, the last UK governor of the territory Chris Patten said Tuesday.

Patten, who oversaw the transfer of Hong Kong from British to Chinese rule in 1997, said Beijing's assertions that the situation in the city was no longer anything to do with London was not the case, due to the binding agreements signed between the countries.

He said Britain should not be afraid of clashing with China over the issue, saying fears it would hurt trade ties were unfounded.

Refusing to criticise Beijing publicly "encourages China to behave badly", he said.

"When China asserts that what's happening in Hong Kong is nothing to do with us, we should make it absolutely clear, publicly and privately, that that is absolutely not the case," said Patten, saying he was "amazed" that the British Foreign Office was not pushing this with Beijing.

The 1984 Joint Declaration set out the terms of the 1997 handover.

- 'Spitting in face' of accord -

"It's certainly, in a sense, to spit in the face of the Joint Declaration to say that it's nothing to do with us -- which is what Chinese officials regularly do," Patten said.

"The Joint Declaration provides obligations on China to us for 50 years."

He said that regrettably, the agreement did not say anything about the method for elections, simply that they would take place.

"It's probably the case that we never really shared with China what we meant by democratic elections, by fair elections. Maybe we should have been more explicit with the Chinese side," said Patten.

He said things in Hong Kong were moving in the right direction, but at a "glacial pace".

He said there was a "seriously sad" and "extraordinary lack of leadership" from Hong Kong's chief executive, claiming there were many things that would "show a willingness to reach a settlement".

Meanwhile London could be offering "sensible suggestions" as to how Hong Kong and China could "get out of the corner they are painting themselves into".

Patten was speaking before parliament's Foreign Affairs Committee, which is looking into Britain's relations with Hong Kong 30 years on from the Joint Declaration.

Protesters have held continuous street rallies for a month, demanding free leadership elections for the semi-autonomous city in 2017.

He said the demonstrators were "a generation that feels they are having their future stolen".

"The aims of the demonstrators should be to get a serious dialogue with the government but things may have gone past that now," Patten said.

"The worry now is that it's become increasingly difficult for anybody to climb down."