The Central Bank of Nigeria (CBN) has warned of attempted fraud related to a fake distribution of the newly launched e-Naira digital currency.

In a statement, the bank said criminals have been sending fraudulent messages to people claiming that it was disbursing e-Naira worth N50bn ($122m; £88m) to citizens.

It denied making such a hand-out.

The e-Naira, a digital version of the naira, is issued by the central bank and is held in an electronic wallet - a first of its kind in Africa to be issued through a government entity.

There have been concerns about its security.

The wallet should be available to download from an app store onto a smart phone.

However, the e-Naira app, called the speed wallet, is unavailable on the Google play store after it was launched on Monday.

The speed wallet enables users to conduct e-Naira transactions but many people complained of hitches while downloading the app.

Several users experienced issues activating their emails, which led to a litany of negative reviews about the app on Google Play store.

A spokesman for Nigeria's central bank told Punch newspaper that the speed wallet app was pulled down to enable an upgrade.

The app is still available on the Apple store for iPhone users.

The digital currency was developed by a Barbados-based tech company, and came eight months after the central bank warned local banks that "facilitating payments for crypto-currency exchanges is prohibited".