San Salvador (AFP) - There are now more than half a million people using El Salvador's bitcoin wallet, President Nayib Bukele announced.

The country of 6.6 million people this month became the first to adopt bitcoin as legal tender alongside the US dollar, which has been the official currency for two decades.

"We currently have more than half a million users (of the Chivo wallet)," Bukele tweeted late Monday.

The "Chivo Wallet" is an electronic application that Salvadorans can download -- earning a $30 equivalent sign-up bonus in the process -- to make cryptocurrency transactions.

Bukele added that the wallet's technical errors had mostly been resolved, and the software would be fully operational in days.

The initial rollout had met with difficulties as the Chivo software had crashed, with bitcoin losing some 17 percent of its value at one point.

But Bukele wrote in his Twitter thread that "every day more and more businesses accept payments in bitcoin or dollars".

The government says the project will give many Salvadorans access to banking services for the first time, and hopes it will shave millions off commissions on remittances, which account for more than a fifth of the country's GDP.

But experts and regulators have highlighted concerns about the cryptocurrency's notorious volatility, its potential impact on price inflation in a nation with high poverty and unemployment, and the lack of protection for users.