Robusta coffee declined to the lowest level in a week on Monday amid signs of more supplies from the world's largest producer of the commodity, Vietnam, and the third biggest, Indonesia. Robusta coffee for July delivery dropped 0.5% to $2.027 a ton at 9:46 a.m. on NYSE Liffe in London as the prices fell to $2.025 a ton earlier today, the weakest since May 13.