Royal Dutch Shell PLC says its third quarter profits fell 4.5 percent due to a one-time tax provision and lower production, though underlying performance improved.

Net profit was $4.46 billion, from $4.67 billion in the same period a year earlier, including the $350 million charge.

Shell said Thursday that on the industry's preferred "current cost of supplies" measure, which strips out the impact of fluctuations in the price of oil, earnings would have risen 27 percent to $5.26 billion.

Shell's main production arm benefited from high-margin oil projects coming on line, Shell says, with "underlying" profit of $5.84 billion. However, production fell by 5 percent to 2.79 million barrels per day.

The company said at its refining arm underlying profits doubled to $1.79 billion on better margins.