A new opinion poll in the US has given Hillary Clinton a nine-point lead over her Republican rival Donald Trump.

The NBC News/Wall Street Journal poll shows she has nearly doubled the five-point advantage she held before the recent political conventions.

Mrs Clinton gets the support of 47% of registered US voters, while Mr Trump see 38% support.

Last month, Mrs Clinton led by a margin of 46% to 41%.

In this latest poll, Mrs Clinton sees a significant advantage among women (51% to Mr Trump's 35%), African-Americans (91% to 1%), all non-white voters (69% to 17%), young voters (46% to 34%), and white voters with a college degree (47% to 40%).

Source: NBC News/Wall Street Journal

While Mr Trump leads among white voters (45% to Mrs Clinton's 40%), older people (46% to 43%), independents (36% to 32%) and white voters without a college degree (49% to 36%).

The two candidates are running nearly even among men, at 43% for Mrs Clinton and 4% for Mr Trump.

But the poll shows Mrs Clinton remains unpopular overall.

She is viewed positively by 37% of voters, while 53% view her negatively.

Mr Trump is even less popular with voters and his favourability rating has remained virtually unchanged since last month.

In the latest poll, 28% of voters give him a positive view, compared to 61% who view him negatively.

The telephone poll of 800 registered voters was conducted July 31st to August 3rd, with a margin of error of +/-3.5 percentage points.