The British pound tumbled dramatically in chaotic trading that included a flash drop in early Asian hours and sustained falls in London. Late morning in Britain, it was down 3% against the US dollar.

The sharp drop in Asia came amid worries about the UK's exit from the European Union that were accelerated by computerised trades, market watchers said. The pound fell more than 6% just after 7 am. Hong Kong time on Friday to as low as $1.1819 from just above $1.26, before recovering above $1.24, according to Thomson Reuters data. But it took another dive in London hours and was down well below $1.23.