(Adds background on share performance, iron ore market and Rio...

(Adds background on share performance, iron ore market and Rio Tinto)

Oct 19 (Reuters) - BHP Group (BHP) on Tuesday posted a nearly 5% drop in iron ore output for the first quarter due to maintenance work at its Jimblebar mine and a shortage of rail labour caused by COVID-19 border restrictions.

But the world's largest miner left its annual production forecast unchanged, unlike rival Rio Tinto (RIO) which last week cut https://www.reuters.com/business/rio-tinto-cuts-2021-iron-ore-shipments-forecast-labour-squeeze-2021-10-14 its shipments forecast due to the tighter labour market.

BHP's production of iron ore from Western Australia on a 100% basis was 70.6 million tonnes (mt) in the three months to September, down from 74 mt a year ago and 72.8 mt in the June quarter.

Growing worries over the finances of the Chinese property market and Beijing's sharper focus on emission controls have halved iron ore prices from a record peak in May, raising concerns that miners' bumper earnings were likely at an end.

BHP shares have sunk by a quarter since the company posted annual results https://www.reuters.com/business/energy/bhp-sell-oil-gas-business-woodside-2021-08-17 in August, in which the miner said it would scrap its dual-listed structure and exit petroleum.

Production at the petroleum business, which is set to be bought by Woodside Petroleum (WPL) , rose 3% to 27.5 million barrels of oil equivalent.

Metallurgical coal output dropped 9% to 8.9 mt, while thermal coal production jumped 17% to 4.2 mt. An acute global shortage of coal, including in China https://reut.rs/3BRV2w6, has driven a surge in the commodity's prices and caused power outages.