The American owners of Tate & Lyle Sugars may be forced to close its London factory because of EU tariffs on sugar imports.

American Sugar Refining (ASR) said there is uncertainty over the viability of the 133-year old Tate & Lyle refinery at Silvertown in east London, which employs 850 people, in the midst of a legal row over the tariffs.

The company, which created Tate & Lyle Sugars after acquiring Tate & Lyle plc's sugar operations last year, is seeking EUR35m (US$47m) that it claims it lost due to tariffs on sugar cane imports. The tariffs, Tate & Lyle Sugars claims, are "prohibitively high" and unfairly stifle competition by favouring domestic producers of beet sugar.

An ASR spokesperson said the European Commission's (EC) tariffs are unfairly putting jobs at risk in Britain and throughout Europe.

He said: "At the moment we are operating at two-thirds capacity. We need access to raw cane sugar and if the EC does not give us a level playing field clearly there's a risk to the future of the business.

"They are putting European and British jobs at risk. We are not asking for anything unrealistic, just a level playing field that achieves the EC's goal of food security and keeps people employed in the industry. That's all we're after."

The EC says the tariffs are in place to guard against shortfalls in supply. A spokesperson said: "The Commission maintains that the regulations (contested by Tate & Lyle Sugars) represent a balanced policy towards the sugar market and will outline in detail policy reasons which led to their adoption."