Three-month non-deliverable forwards showed the naira trading at around 278 per dollar, weakening 2.2 percent on the day, and the weakest since June 3.
One-month non-deliverable forwards moved too with the naira 1.5 percent lower, trading at around 239 per dollar.
The official naira rate is currently fixed at around 198 to the dollar.
The country's central bank has floated the idea of ditching that peg and moving to a different, weaker exchange rate for petrol imports, but few firm details have emerged.