Donald Trump has said his famous wall might not stretch along the whole US-Mexican border because America is protected by 'mountains and vicious rivers'.

The wall was his stand-out promise on his manifesto in the race to the White House, as he promised to build a 2,000-mile structure funded by Mexico.

But since he was unveiled as the 45th President, he has appeared tentative in coming forward with exactly what his grand plan will look like, and now he says the geography of the area would take care of drug traffickers.

Donald Trump has said his famous wall might not stretch along the whole US-Mexican border because America is protected by 'mountains and vicious rivers

It was his stand-out promise on his manifesto in the race to the White House, saying he would build the enormous structure almost 2,000 miles in the length and that the Mexicans would pay for it

In a new interview with Fox News' Sean Hannity, the President-elect said: 'Now, there are certain places you don't need a wall, because you have, you know, you have mountains, you have other things.

'You have large and rather vicious rivers.

'But, no, we're building a wall. It's going to be a real wall, because we're going to stop the drugs from coming in.'

Speaking in Cincinnati, Ohio, kicking off his 'Thank You' tour, he did not specify where the wall would be substituted with the natural elements of the landscape.

Since he was unveiled as 45th President of the US, Trump has appeared tentative in coming forward with exactly what his grand plan will look like, and now he said the geography of the area would take care of drug traffickers

Trump went on to say his wall would prevent illegal immigration but allow legal immigrants to cross the border

Trump went on to say his wall would prevent illegal immigration but allow legal immigrants to cross the border, saying: 'We're going to have a real wall and we're going to stop what's happening, because what's happening in our country is very sad in so many different ways.'

Last month, the President-elect discussed the possibility that some parts of the wall will have to be fencing in order to keep costs down.

Interviewer Leslie Stahl on CBS's 60 Minutes asked Trump whether the wall could be 'part wall, part fence?'

He replied: 'There could be some fencing.'

The nearly 2,000-mile US-Mexican border currently has high walls in some sectors, fencing in others, along with electronic and human surveillance in other portions, including vast desert areas.

Trump kicked off his presidential campaign by outlining his uncompromising stance on immigration.

He proposed building a wall – and making Mexico pay for it – to keep illegal immigrants out of the United States because 'when Mexico sends its people,' he said, they're sending 'rapists' and 'criminals.'