HAMBURG - A Syrian state grains agency has issued an international tender to exchange 100,000 tonnes of Syrian durum wheat for 100,000 tonnes of soft wheat for bread making sourced from Russia, European traders said on Monday.

The deadline for submission of offers in the tender from Syria's General Establishment for Cereal Processing, Storage and Trade (Hoboob) is Sept. 17, traders said.

Syria's wheat and barley crops almost doubled this year following favourable rain and better overall security but food security remains a challenge as conflict in the country continues, the United Nations Food and Agriculture Organization (FAO) and the World Food Programme (WFP) said on Sept. 5. 

A government source told Reuters on Monday that of the estimated 2.2 million tonnes produced this year, Hoboob had purchased 900,000 tonnes. 

Wheat in Syria is used in the production of flat bread, a subsidised staple for a population that has suffered under a conflict estimated to have killed several hundred thousand people and forced millions to flee their homes since 2011.

The steady fall in output has put President Bashar al-Assad's government under increasing pressure to import grain - a process complicated by financial sanctions. Trade with his ally Russia poses fewer problems.

Offers valuing the soft wheat in this latest barter tender must be submitted in U.S. dollars.

The difference in value between the hard and soft wheat will be settled under a financial arrangement to be agreed. Durum wheat is normally more expensive than soft wheat.

The winning company must provide a bid bond for 10% of the soft wheat value, also in dollars.

Hard amber durum wheat of 12% minimum protein is being offered. Soft wheat with at least 11.5% protein is being sought.

(Reporting by Michael Hogan; additional reporting by Maha El Dahan in Dubai; editing by Jason Neely and Louise Heavens) ((michael.j.hogan@thomsonreuters.com; +49 172 671 36 54; Reuters Messaging: michael.hogan.thomsonreuters.com@reuters.net))