Riverside’s former under-23 world champion was among the leaders after the 750-metre swim in Hamburg, but later demanded answers for a chaotic sequence of events.

Going on to finish fifth in a race won by Spain’s two-time series champion Mario Mola, Birtwhistle took to Twitter to express his frustration.

“Two starting horns, kayaks moved out to block the field (race restart protocol), athletes stop swimming.. and then the race continues? @worldtriathlon where is the explanation for this? At the highest level of racing, this is not acceptable,” Birtwhistle wrote.

The 23-year-old cycled 21km in 29:27 before running a 14:21 5km to finish 18 seconds behind Mola’s 53:24.

Now fourth on the WTS rankings, Birtwhistle will be hoping to add further success in the world mixed relay series.