The disruption occurred from around 7am to 6pm, according to Chinese daily Lianhe Zaobao.
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In its Facebook page at 8pm yesterday, Jem posted:
"Jem had a power outage this morning, 21 March and we attended to it immediately.
"Some retailers on level 3 and basement 1 were affected.
"We are now pleased to confirm that power to the affected retailers has now been fully restored and it's now business as usual."