The FBI's director has been warned he may have broken US law by announcing an investigation into emails potentially linked to Hillary Clinton.

A senior Democrat's accused James Comey of illegally influencing the upcoming presidential election.

Meanwhile the FBI's obtained a warrant to begin reviewing emails from a Clinton aide, and whether they contain classified government information.

According to The Wall Street Journal, it's focusing on around 650-thousand messages, found on the laptop of former congressman Anthony Weiner - who is married to one of Mrs Clinton's top aides.

Speaking at a rally in New Mexico, Donald Trump has again used the revelations to criticise his rival: