SINGAPORE (Reuters) – Singapore plans to give a wearable device that will identify people who had interacted with carriers of coronavirus to each of its 5.7 million residents, in what could become one of the most comprehensive contact-tracing efforts globally.

Testing of the small devices, which can be worn on the end of a lanyard or carried in a handbag, follows limited take-up of an earlier smartphone-based system and has further fuelled privacy concerns about contact tracing technology.

The tiny city-state, with one of the highest COVID-19 caseloads in Asia, is one of many countries trying to use technology to allow them to safely reopen their economies.

Singapore will soon roll out the device, which does not depend on a smartphone, and “may then distribute it to everyone in Singapore,” Vivian Balakrishnan, the minister in charge of the city-state’s smart nation initiative, said on Friday.

The government did not specify whether carrying the device would be mandatory.

The government’s earlier TraceTogether app encountered problems, especially on Apple (AAPL.O) devices where its operating system suspends Bluetooth scanning when the app runs in the background. Balakrishnan said repeated discussions with Apple failed to resolve the problem.

The pivot to wearables is a signal that Singapore has no immediate plans to adopt contact-tracing technology from Apple and Google (GOOGL.O) rolled out last month, which has several restrictions designed to protect users’ privacy.

Michael Veale, a lecturer in the law on digital rights and regulation at University College London who has been involved in developing contact-tracing apps, said Singapore’s move into wearables presented “accountability and privacy concerns.”

“Users will likely find it hard to scrutinise what the device is actually doing, or what information the back-end server uses or links,” Veale said.

Singapore has said data collected through its earlier app is encrypted and stored locally in the user’s phone, and will only be transferred to authorities if the individual is confirmed to be infected with COVID-19.

Some businesses have already adopted wearables for contact tracing in locations where smartphone usage is restricted, while governments like Bahrain and Hong Kong have used them for monitoring people under quarantine.

Vendors pitching wearables include Accent Advanced Systems, Kerlink, Microshare Inc and TRACEsafe Technologies Inc, though the companies have declined to comment on potential customers.

David Su, CEO of wireless chips firm Atmosic, said he expected “multiple governments, if not all governments in Asia” to adopt wearables because they are an affordable and reliable way to ensure widespread automated contact tracing.

A simple wristband with a Bluetooth chip, battery and some memory could cost about $10, or possibly less, according to vendors.