US authorities have arrested a man in Florida over alleged threats to kill Democratic presidential candidate Barack Obama as well as President George W Bush.

Raymond Hunter Geisel, 22, was interviewed on 1 August by agents of the US Secret Service's Miami field office and arrested a day later.

According to a Secret Service affidavit, Mr Geisel, using a racially derogatory term, told a fellow student that if Senator Obama gets elected: ‘I'll assassinate him myself’.

Another student in the class told a Secret Service agent that she had heard Mr Geisel say that ‘he hated George W Bush and that he wanted to put a bullet in the President's head’.

A search of Raymond Geisel's car and home yielded a machete, a loaded 9mm handgun, a combat-style hatchet, knives, 40 rounds of 9 mm armour-piercing handgun ammunition, two canisters of tear gas, and other items, according to the document.

During his interview, Raymond Geisel denied making threats against Senator Obama or President Bush.

However he did state that 'if he wanted to kill Senator Obama he simply would shoot him with a sniper rifle, but then he claimed that he was just joking,’ according to the affidavit.

Later, he signed a statement that he did not say he was going to kill any President or Senator Obama.

Raymond Geisel will face prosecution under a US law forbidding making threats against the president or a major candidate for the office of president, the affidavit said.

Asked how many such threats occur each year, US Secret Service spokesman Ed Donovan said US Secret Service policy was not to disclose a precise number but said that ‘many, many threats are investigated each year.’