By Chijioke Ohuocha LAGOS (Reuters) – PayPal has signed up tens of thousand of Nigerians in its first week of operating in Africas biggest economy, with consumers already purchasing items from Britain, China and the United States via its online platform, a company official said. E-commerce remains in its infancy in most of Africa but is growing exponentially with the advent of online retailers such as Jumia, partly owned by South African phone operator MTN, and a growing middle class with money to spend. Citizens of Africas most populous nation could not buy goods directly from foreign merchants before the launch by PayPal, the payments unit of online auctioneer eBay Inc. We have seen great uptake by Nigerians … in terms of coverage, Malvina Goldfeld, PayPals head of business development for sub-Saharan Africa, said in Lagos on Tuesday. PayPal entered Nigeria and 10 other nations last month, providing online payment alternatives for consumers via mobile phones or PCs in markets often blighted by financial fraud.