China's manufacturing activity contracted in April, an official survey showed on Wednesday, reversing two months of recovery and keeping alive calls for further stimulus as Donald Trump's 145% tariffs called time on producers front-loading shipments. The official purchasing managers' index (PMI) fell to 49.0 in April versus 50.5 in March, below the 50-mark separating growth from contraction, and missing a median forecast of 49.8 in a Reuters poll.