China's iron ore futures recovered early losses to extend gains for a fourth session on Thursday, on renewed demand optimism as steel mills look towards restocking for raw materials.

The most-active iron ore futures contract on the Dalian Commodity Exchange, for January 2020 delivery, closed up 1% at 628 yuan ($88.90) a tonne, its highest since Oct.16.

Other steelmaking ingredients also rose, with Dalian coking coal edging up 0.4% to 1,257 yuan a tonne and coke gained 1% at 1,781 yuan.

"While Tangshan cities are facing production curbs to reduce pollution, other steel plants are reported to increase their production because of attractive profitability," Argonaut Securities said in a note.

China's top steelmaking province of Hebei had implemented overnight inspections on illegal industrial works and emissions as an effort to crack down pollution, according to state-backed People's Daily.

But the anti-pollution plan for this autumn-winter heating season in northern China is still not enough to offset last year's sharp increase, official data showed.

The most-active construction steel rebar contract on the Shanghai Futures Exchange, for January delivery, inched down 0.2% to 3,318 yuan.

Futures for hot-rolled coil, used in cars and home appliances, rose 1.1% to 3,356 yuan per tonne.

Stainless steel, for February delivery, edged up 0.3% at 15,005 yuan a tonne.

Prices for spot cargoes of benchmark iron ore with 62% iron content for delivery to China rebounded to $86.5 a tonne on Wednesday.

China's imports of semi-finished steel surged in September as a crackdown on scrap shipments saw Chinese buyers scoop up alternative forms of the metal from other Asian countries at favourable prices.

China's steel industry expects to face weak demand amid ample supplies in the final quarter of the year, with continued output restrictions and slow industrial activity during the winter heating season, a state newspaper cited participants at an industry conference organised by China Iron and Steel Association.