"It's breaking down again, the funds are selling and roasters don't seem to be chasing the price," one floor source said.
London's benchmark September contract settled down $6 to reach $678 a tonne.
The contract kept within a range of $673 to $682 in volume of 2,574 lots out of a total of 8,407.
Analysts predict that the trend could continue down to the $650 level for the first time since October 2002.
On fundamentals, a coffee surplus is expected for the 2003-2004 agricultural year and participants say a rally in bean values is unlikely unless the Brazilian harvest is struck by a late frost.