Ukraine has warned of a deeper-than-expected drop in its wheat harvest this year, signalling that winterkill may have wrought worse damage to the Black Sea grain powerhouse than analysts have factored in.

Viktor Slauta, the Ukrainian deputy prime minister, told reporters that the country's wheat production "may be 15% lower than in 2009".

With last year's crop pegged at 20.9m tonnes, the forecast implies a 2010 harvest of well below 18m tonnes, taking it significantly beneath external forecasts.

UkrAgroConsult, the Kiev-based analysis group, has pegged the crop at 18.86m tonnes, with the US Department of Agriculture forecasting a 19.5m-tonne harvest.

Winterkill debate

Mr Slauta, cited "large losses in winter wheat crops", a topic of some debate among Ukraine's crop-watchers after a cold and prolonged winter.

A USDA report earlier this week said that "various forecasts over the past two months have estimated winterkill at anywhere from 3-30%", although the bulk of the losses have been attributed to barley and rapeseed, which are more susceptible to cold.

However, some analysts have warned that, with autumn-sown crops planted in dry conditions, some wheat may have headed into the winter in a weaker-than-normal state.

Furthermore, many farmers have taken to sowing winter crops late, to narrow the window before winter in which they are susceptible to insect pests and disease, and so enable savings on pesticide bills.