American president, Donald Trump has shaken up campaign staff amid falling poll numbers less than four months before the US presidential election, replacing his campaign manager Brad Parscale with veteran Republican operative Bill Stepien.

The move came following a rally in Tulsa, Oklahoma, last month that drew an unexpectedly low crowd of about 6,200 people after Mr Parscale bragged that more than a million people had requested tickets.

Meanwhile, China has accused the US of "gangster logic" after Mr Trump ordered an end to Hong Kong's special status in US law in response to Beijing's imposition of new security legislation on the territory.