Republican presidential nominee Donald Trump today accused Hillary Clinton of leaving behind a legacy of "death, destruction, terrorism and weakness" as former US secretary of state and blamed her "bad judgement" for the rise of IS and chaos in Iraq, Libya, Syria and Egypt.

"This is the legacy of Hillary Clinton: death, destruction, terrorism and weakness. America is far less safe – and the world is far less stable – than when Obama made the decision to put Hillary Clinton in charge of America's foreign policy. I am certain it is a decision he truly regrets," the 70-year-old real estate tycoon said in his acceptance speech here as the Republican presidential candidate.

"Her bad instincts and her bad judgement – something pointed out by (Vermont senator) Bernie Sanders – are what caused the disasters unfolding today," he said.

Reviewing Clinton's record, Trump said in 2009, IS was not even on the map and the situation across the Middle East was stable. He blamed Clinton for giving rise to the IS and for sowing chaos in Iraq, Libya, Syria and Egypt.

"After four years of Hillary Clinton, what do we have? IS has spread across the region, and the world. Libya is in ruins, and our ambassador and his staff were left helpless to die at the hands of savage killers. Egypt was turned over to the radical Muslim brotherhood, forcing the military to retake control. Iraq is in chaos.

"Iran is on the path to nuclear weapons. Syria is engulfed in a civil war and a refugee crisis that now threatens the West. After fifteen years of wars in the Middle East, after trillions of dollars spent and thousands of lives lost, the situation is worse than it has ever been before," he said.

He said Clinton's legacy does not have to be US legacy.

"The problems we face now – poverty and violence at home, war and destruction abroad – will last only as long as we continue relying on the same politicians who created them."

Trump said while Clinton's message was that things will never change, his message is that things have to change. "And they have to change right now," he said amid applause.

Clinton fired off an icy rebuke on Twitter during Trump's speech, telling him: "We are better than this."

Countering Trump's attack, the Clinton Campaign accused him of painting a dark picture of an America in decline and said that his speech was yet another reminder that he is temperamentally unfit and totally unqualified to be President.

"Tonight, Trump painted a dark picture of an America in decline. And his answer – more fear, more division, more anger, more hate - was yet another reminder that he is temperamentally unfit and totally unqualified to be President of the US," Clinton Campaign chairman John Podesta said.

"He offered no real solutions to help working families get ahead or to keep our country safe, just more prejudice and paranoia. America is better than this," he said.

"America is better than Donald Trump. Next week in Philadelphia, Democrats will focus on issues, not anger. We'll offer a positive vision for the future based on lifting America up, not tearing Americans down," he added.