In a blow to Donald Trump, a group of 50 Republican national security experts, including former top spy masters and diplomats, has said the White House nominee would be a dangerous President and would put the country's safety at risk.

However, Trump sought to dismiss their charges by saying that these "Washington elites" should look for answers on why the world has become a mess.

In a statement issued yesterday, the group of national security experts said, "None of us will vote for Donald Trump. From a foreign policy perspective, Trump is not qualified to be the President and Commander-in-Chief. Indeed, we are convinced that he would be a dangerous President and would put at risk our country's national security and well-being." "Most fundamentally, Trump lacks the character, values, and experience to be President. He weakens the US' moral authority as the leader of the free world," said the letter which has been signed by individuals who served in senior national security and foreign policy positions in Republican administrations, from Richard Nixon to George W Bush.

The statement added that the 70-year-old business tycoon appears to lack basic knowledge about and belief in the US Constitution, US laws and US institutions, including religious tolerance, freedom of the press and an independent judiciary.

Claiming that Trump lacks the temperament to be the President, the statement alleged he has demonstrated repeatedly that he has little understanding of America's vital national interests, its complex diplomatic challenges, its indispensable alliances and the democratic values on which the US foreign policy must be based. Trump, the statement said, is unable or unwilling to separate truth from falsehood. He does not encourage conflicting views.