European wheat futures extended a rally on Tuesday to their highest in a year as sustained export demand, with prices supported by logistical bottlenecks in France and plans by Russia to cap grain shipments.

Benchmark March milling wheat on the Paris-based Euronext exchange unofficially closed 1 euro, or 0.5%, up at 194 euros ($215.90) a tonne.

It earlier hit 195 euros, the contract's highest level since December 2018. In terms of spot prices, that would be the highest in nearly a year. Logistical difficulties in France, linked to rail and port strikes over pensions reform, ensured cash premiums in export zones remained steady.

Two fires at grain port terminals, one on a loading crane in Nantes on Monday and another at a silo in Rouen on Sunday, had also slowed vessel loading ahead of a three-day strike by dockers from Tuesday, traders said. "Prices are well supported with the logistical problems in France," one futures dealer said. "The Russia headlines also caught attention."

Russia's agriculture ministry is looking to set a non-tariff quota for grain exports of 20 million tonnes for the rest of the season. However, traders said that Russian authorities' proposed ceiling on grain exports for the first half of 2020 would allow ample room to ship the country's remaining wheat surplus.

In Germany, underlying prices were firm despite cash premiums in Hamburg being cut as buyers declined to accept the full rise in Euronext prices. Standard bread wheat with 12% protein for January delivery in Hamburg was offered for sale at 4 euros over the Paris March contract, down from 5 euros over Paris on Monday. Buyers were offering up to 3.50 euros over Paris.

"Premiums were cut by about 1 euro, but Paris prices have risen by more than this so far this week, so underlying prices were still higher," one German trader said. "There is a good programme of ships loading wheat in German ports and supplies are being called up to load the vessels. This continues to support prices." One vessel will take on about 60,000 tonnes for Iran this week after another vessel loaded about 50,000 tonnes for Iran last week. Iran made major purchases in late 2019.