(Bloomberg) -- Tangshan, a steelmaking hub about 100 miles from Beijing, has re-enforced Covid-19 lockdowns in some districts just over a week after lifting city-wide curbs.

The city locked down five districts from 6 a.m. Tuesday and will conduct mass-testing, the local government said, after reporting 29 cases coronavirus cases on Monday. Tangshan hosts about 13% of China’s steel output, and some production was halted during a 20-day lockdown that ended on April 11.

The partial reversal will raise fresh concerns about steel output, and underscores China’s difficulties in stamping out omicron’s spread. Authorities across the nation are battling coronavirus flare-ups with tough mobility restrictions that are hurting factories, snarling supply chains and weighing on the economy.

Singapore iron ore futures rose 0.3% to $155.35 a ton by 9:36 a.m. local time.

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