Royal Dutch Shell
Royal Dutch Shell shares took a knock after the report that its Nigeria business was weakening on heightened security concernsReuters

Oil major Royal Dutch Shell has reported a robust performance in the second quarter of 2014 as its profits more than doubled compared to a year earlier.

Shell CEO Ben van Beurden praised the second quarter performance and said the company had progressed throughout the year.

"Our financial performance for the second quarter of 2014 was more robust than year-ago levels but I want to see stronger, more competitive results right across the company," he said in a statement.

Even if one-off items such as asset sales and on-off charges were excluded from the report, the Anglo-Dutch oil and gas giant boosted profits by 33% at $6.13bn, compared to $4.6bn in the last year.

The results reflect higher prices on some products and a boost in liquid petroleum production.

Shell's results show improvement on its first quarter performance, where profits plunged to $4.5bn from $8bn a year earlier.