Anglo-Dutch oil giant Shell on Thursday announced second quarter earnings of $2.4bn compared with $6b in the year-earlier period.

Underlying current cost of supplies earnings were $4.6bn for the quarter, a 221% decrease from the second quarter of 2012. Net profit halved to $1.7bn.

Production of oil and gas fell 1% to the equivalent of 3.06 million vats a day.

CEO Peter Voser called the results ‘clearly disappointing’. ‘Higher costs, exploration charges, adverse currency exchange rate effects and challenges in Nigeria have hit our bottom line,’ he said in a statement.