David Cameron's insistence that there will not be another Scottish independence referendum before 2020 is "his opinion" as he "can't stand in its way", SNP leader Nicola Sturgeon has said.

The First Minister has been touring media organisations while on a visit to Hong Kong, attacking the UK Government's efforts to deflect persistent questions about a second referendum after a decisive No vote in September was followed by a Nationalist landslide in May.

Ms Sturgeon told US broadcaster CNBC that "time will tell" if there is another referendum before 2020, and she said Scotland will "inevitably" want to revisit the question if the UK votes to leave the European Union against its will.

Earlier, in a speech to the Hong Kong Foreign Correspondents' Club, Ms Sturgeon said "no politician has the right to stand in their way" if Scotland wants another referendum.

The Prime Minister said this week that last year's referendum was "decisive" and he does not see the need for another one, flatly ruling out a second poll in the current Westminster parliament.

Ms Sturgeon told CNBC: "That's his opinion and he's entitled to it.

"Time will tell because this is the fundamental point I am making. I want Scotland to be independent, but just because I want it, doesn't make it happen.

"There will only be another referendum if a majority of people in Scotland want it.

"But the reverse of that is also true. If a majority of people do want it then David Cameron has no right to stand in the way of that happening.

"So I can't impose another referendum in Scotland against the will of the people of Scotland, but David Cameron can't stand in its way."

She added: "If we ended up in a position where Scotland was effectively being taken out of the EU against our will then I think inevitably people would want to look again at the question of independence for Scotland."

Last year's referendum was agreed by Westminster following the SNP's Holyrood landslide in 2011 with a manifesto promising a referendum, and Ms Sturgeon has faced pressure to reveal whether she will pledge another vote in her 2016 manifesto.

Mr Cameron indicated that a decision by the Scottish Government to unilaterally hold another referendum would not be legitimate, while Scottish Secretary David Mundell said it is not for the SNP to determine whether the people of Scotland want another referendum.

In her speech to the Hong Kong Foreign Correspondents' Club, Ms Sturgeon said: "No politician can impose a referendum on Scotland, no matter how much some of us would like Scotland to be independent.

"And it's worth pointing out that the reverse is also true. If the Scottish people do vote in future to have another referendum, no politician has the right to stand in their way."

Ms Sturgeon said the election of 56 SNP MPs at the general election has "left no doubt about the desire of people in Scotland for a much more empowered Scottish Parliament".

She added: "That election result didn't provide a mandate for independence or a further referendum - I was always absolutely clear about that.

"But it did reaffirm the importance of Scotland having a much stronger voice in UK affairs, and it left no doubt about the desire of people in Scotland for a much more empowered Scottish Parliament."

She added: "If in Scotland we faced exit from the EU, effectively against our will - something which the polling suggests could happen - it would not be at all surprising if that caused a swell of demand for a further independence referendum."