LAGOS: Nigeria's central bank stepped up its defence of the ailing naira on Friday, asking 21 commercial lenders to bid for $3 million each in a move to prop the local currency, dealers said.

The naira firmed 2.5 pct to 169.60 against the dollar in volatile trade after the intervention, having earlier touched 173.77. It has fallen 8 percent so far this year.

Copyright Reuters, 2014