Donald Trump has lambasted Hillary Clinton as a "world-class liar" in a speech attacking the former Secretary of State.

The Republican White House candidate accused his Democratic rival of "theft" while she was America's top diplomat.

The tycoon also labelled his opponent possibly "the most corrupt person ever to seek the presidency of the United States".

"She ran the State Department like her own personal hedge fund, giving favours to oppressive regimes," he claimed.

He said she had spent "her entire life" raising money for special interests and has "taken plenty of money out for herself".

Mr Trump's speech on Wednesday at one of his Manhattan hotels marked an official opening salvo against Mrs Clinton ahead of November's general election.

It comes a day after she made a speech warning that Mr Trump would send the US economy into a recession, if elected.

Mr Trump railed against "Hillary-backed" free trade agreements, such as Nafta, which was signed by her husband, former President Bill Clinton.

He warned that if elected she would approve the Trans-Pacific Partnership, which he predicted would destroy millions more US jobs.

"We will never be able to fix a rigged system by counting on the people who rigged it in the first place," Mr Trump said.

He told supporters Mrs Clinton had "sold out our workers" and "she gets rich by making you poor".

Mr Trump also pilloried her on foreign policy, accusing her of having "unleashed ISIS".

And he blamed her for the 2012 death of a US diplomat in Benghazi, Libya.

"Her decisions spread death, destruction and terrorism everywhere she touched," he said.

Mr Trump added that she had "almost single-handedly destabilised the entire Middle East".