LAGOS (Reuters) - Nigeria's naira firmed against the dollar on Wednesday as Chevron's local unit sold the U.S. currency and offshore funds bought local debt, dealers said. The naira was trading 0.34 percent higher at 161.60 naira to the dollar at 1116 GMT, from Tuesday's close of 162.15 naira. Dealers said the local unit of U.S. oil firm Chevron sold about $18 million to banks, while offshore investors participating in a debt auction on Wednesday sold an undisclosed amount of dollars. Nigeria was due to auction 200 billion naira ($1.2 billion) in treasury bills and bonds on Wednesday.[ID:nL6N0N83FK][ID:nL6N0N83VQ] Offshore funds have renewed their appetite for Nigerian assets, dealers say, after the West African country rebased its GDP, overtaking South Africa as the continent's biggest economy and making it a more attractive destination for investors.[nL6N0MY0LT]