Pedestrians pass an information board outside Anglo American's offices in Johannesburg, South Africa.

London - Miner Anglo American posted an increase in its copper and iron ore production in the first quarter of 2014, but its platinum output slumped, hit by a strike at its South African operations.

Copper output rose 18 percent from the same period a year earlier to 202 000 tons, on the back of higher ore grades from the Los Bronces and Collahuasi mines in Chile. Anglo raised its 2014 copper production output guidance to 710 000-730 000 tons from 700 000-720 000.

Iron ore output totaled 11.3 million tons in the first quarter, up 10 percent from a year before when production at the Sishen mine in South Africa was curbed following a strike in late 2012.

In platinum, where Anglo is slashing jobs and mothballing mines to improve the unit's profitability, equivalent refined platinum production fell 39 percent to 357 000 ounces, largely due to a prolonged strike affecting some of its South African operations.

Anglo lowered its platinum guidance for the year. It now expects to produce about 2.1 million ounces of refined platinum equivalent, down from expectations of 2.3 - 2.4 million ounces previously. - Reuters