By Helen Reid LONDON (Reuters) -Fast-fashion retailer Shein's executive chairman Donald Tang told investors in a letter on Monday that "growth remains strong" despite the United States ending duty-free treatment of low-value ecommerce packages from China and hiking tariffs.

Shein, China's much-maligned fast fashion giant, is trying to reassure investors after US President Donald Trump's decision to end the de minimis

Fast-fashion retailer Shein is under pressure to cut its valuation to about $30 billion, according to people familiar with the matter, having in the past been valued at more than three times that amount.