Robusta coffee traded in London slipped on Thursday falling to the weakest level in nearly a week amid speculation that Vietnamese farmers may begin selling the commodity as the harvest in the top world's producer advances. Robusta coffee expiring in January slid 0.7% to $1,455 a metric ton as of 11:25 a.m. on London's NYSE Liffe, while Arabica coffee with delivery in March dropped 0.2% to $1.057 a pound on ICE Futures U.S. in New York.