A bird flies by the Vedanta office building in Mumbai in this file picture.

London - London-listed mining and oil company Vedanta Resources Plc's third-quarter revenue fell 3 percent as an unplanned shutdown at its international zinc unit hit production.

Revenue in the quarter ended December 31 fell to $3.45 billion from $3.57 billion a year earlier.

Revenue from zinc international was down 39 percent, with overall revenue from zinc 14 percent lower during the quarter.

Third-quarter production at its zinc international business fell 19 percent due to a maintenance shutdown at Skorpion in Namibia in November and December after a tank failure, the company said.

The unit accounts for about 5 percent of total revenue.

Vedanta, controlled by Indian billionaire Anil Agarwal, said group core earnings or earnings before interest, taxes, depreciation, and amortisation (EBITDA) increased 3 percent to $1.14 billion with oil and gas as the key contributor.

Core earnings from the oil and gas unit, which accounts for about 22 percent of revenue, rose 1 percent to $615.7 million.

The miner also said it was ramping up iron-ore production in the southern Indian state of Karnataka to a run-rate of around 0.5 million tonnes per month, and expected to commence sales through auctions shortly.

Vedanta resumed mining iron ore in Karnataka in December following clearance from a court-appointed panel.

The company simplified its byzantine structure last year when it overhauled its web of subsidiaries and created Sesa Sterlite - an umbrella unit that groups most of its assets.

Shares in the company were down 1.8 percent at 822 pence at 11:05 SA time on the London Stock Exchange on Friday.

They had dropped as much as 4 percent in early trade. - Reuters