US presidential hopeful Hillary Clinton has continued to attack Donald Trump, saying that what the presumptive Republican nominee has said about foreign policy is not just offensive, but dangerous, too.

Speaking at a campaign rally in Kentucky, Clinton said the billionaire businessman's stance to temporarily ban Muslims from entering the US hurts the ability for a president to negotiate deals in the Middle East.

"How do we put together a coalition to take out Isis when members of that coalition are majority Muslim nations? So what Trump says about foreign policy is not just offensive, it's dangerous," she said.

Clinton, a former secretary of state, has said Trump would have to offer policy specifics in ahead of the 8 November presidential election and criticised him for his foreign policy statements.

"I don't think most Americans want a loose cannon in the Oval Office. And when he has said he wants more countries to have nuclear weapons, when he has said he would have us use nuclear weapons against Isis which isn't even a state, when he would pull us out of Nato, which is our most important military alliance, that doesn't just raise red flags that raises danger signals that people have got to pay attention to," Clinton noted.

Recent polls suggest that a Trump/Clinton matchup could be a tight race. The two candidates were in a dead heat in the three key swing states of Florida, Ohio and Pennsylvania in a Quinnipiac University poll earlier in May.