Delta Air Lines fell short of profit estimates for the three months to June 30th as fuel costs grew at a higher rate than revenue.

Net income at Delta stood at $198 million, or $0.23 per diluted share, for the second quarter, compared with $467 million a year earlier.

Quarterly revenue rose 12 per cent to $9.15 billion.

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Delta’s operating expense increased $1.4 billion year-on-year, with more than $1 billion of this increase attributable to a 39 per cent increase in fuel prices.

The remainder of the cost increases were primarily driven by maintenance volumes and higher revenue-related expenses.

“We have seen unit cost growth from not only high fuel prices, but also maintenance volumes and revenue-related expenses,” said Hank Halter, Delta’s chief financial officer. 

“We are moving aggressively to stem this cost growth with a target of bringing our non-fuel unit costs to 2010 levels by the end of the year.”

Shares in Delta fell following the news, closing down 5.1 per cent at $7.61, below their year low of $7.78, after trading as low as $7.29 earlier in the session.

Delta - the second biggest carrier in the world behind United Continental - has invested in new aircraft seats and better food and wine offerings to boost revenue in recent months.