Miners are the biggest fallers in the FTSE 100 so far today.
Rio Tinto, BHP Billiton and Anglo American are all off 3% or more.
Reuters links this to plans by Brazilian miner Vale to partially resume processing operations at Vargem Grande complex.
Production had fallen - forcing prices higher - after the collapse of the Brumadinho dam in January, which killed at least 248 people.
Reuters notes that a number of brokers are pointing to an increase in iron ore supply in the future.
Earlier this month a judge in Brazil ordered Vale to pay compensation for all damages