PARIS- Grain crops in the European Union have mostly acquired greater frost resistance during cold spells since December, but an unusually mild winter in the southeast of the bloc was limiting plant sturdiness there, the EU's crop monitoring service said.

So-called winter crops typically gain hardiness in order to withstand freezing conditions before resuming their growth in spring.

"The frost tolerance of winter cereals has increased considerably since December in eastern, northern and central Europe, as well as the northern part of the Iberian Peninsula," the MARS service said in a monthly report issued on Monday.

In Spain, which was battered by a snowstorm earlier in January, some localised frost damage to crops is likely to have occurred in the north, said MARS, projecting similar minor damage in other EU regions including northern Romania.

Frost tolerance remained weaker than usual in southeastern Europe and Turkey, and warmer-than-average winter temperatures were forecast to continue there this week, MARS said.

A lack of sturdiness leaves crops vulnerable to subsequent cold snaps, although MARS said the long-range weather forecast for February, March and April suggested likely warmer-than-usual conditions in most of Europe, particularly in the eastern Mediterranean.

In France, significant rainfall is expected across the country this week, MARS said. That could keep the EU's biggest grain producer on track for a bumper wheat harvest this year after a favourable autumn sowing campaign.

(Reporting by Gus Trompiz; Editing by Kirsten Donovan) ((gus.trompiz@thomsonreuters.com; +33 1 49 49 52 18; Reuters Messaging: gus.trompiz.thomsonreuters.com@reuters.net))