EU sugar beet production surged last year after farmers increased the planted area ahead of the ending of the bloc's sugar quota system, and as favourable weather boosted yields.

Initial indications were that the planted area in the EU would be stable this year, with many growers following commitments in advance contracts with sugar makers rather than reacting to weather or falling sugar prices.

But planting delays could curb yields in the autumn harvest.

"The worry is we risk losing yield potential," Francois Thaury of consultancy Agritel said.

"Planting takes place a bit earlier in France so delays there are more significant, but the situation is similar in other EU countries," he said.

Sugar beet growers group CGB said less than 7 percent of the expected area in France had been planted by Wednesday, whereas on average in the previous five years half of plantings had been completed by March 23.

Tereos, France's largest sugar marker, said its cooperative members had done virtually no planting as of Tuesday, compared with 50 percent a year ago.

A very wet winter in France left many fields drenched. With showers forecast for the week ahead, farmers may struggle to sow before the optimal sugar beet planting window ends in early April, analysts said.

The CGB, which expects the French area to be stable versus last year, estimates the crop has already lost 1.5 million tonnes in potential versus last year's record 45 million.

In Germany, sowing was starting and running slightly late after recent cold snaps and persistent damp conditions.

"The delay is not serious at the moment but fields are still wet, especially in north Germany, and need a few days of sunny, warm weather to allow beet sowing to gather speed," one German analyst said.

German farmers increased sowings last year by 22 percent to 407,000 hectares.

In Poland, unfavourable weather has also delayed the start of sowings by one to two weeks, said Rafal Strachota, director of Polish sugar beet growers' association KZPB.

"Temperatures are not conducive to the start of beet sowing. However, the first sowing has already taken place in individual cases," Strachota said.

In 2018, Poland's beet area may be slightly larger than the 231,000 hectares planted in 2017, he said.

Progress was also slow in Britain.

"The start of drilling this season's crop has been slowed down by the recent wet conditions and is currently about two weeks behind last season's crop," said Colm McKay, Agriculture Director at British Sugar.

"However, we are still in the ideal window for drilling and expect to make further progress soon."

(Additional reporting by Sybille de La Hamaide in Paris, Michael Hogan in Hamburg and Nigel Hunt in London; Editing by Mark Potter)

By Gus Trompiz