Fast-growing budget airline Norwegian Air Shuttle swung to a surprise net profit in the second quarter as it continues to ramp up its transatlantic business. 

Europe's third-largest budget airline by passenger numbers is trying to crack the transatlantic market by undercutting established rivals.

But it has faced pressures to control costs and shore up its balance sheet in the face of stiff competition. 

The company posted a net profit of 300 million crowns ($37.07m) in the second quarter.

This compared with a loss of 691 million crowns a year ago and largely above expectations for a loss of 535 million crowns in a Reuters poll of analysts. 

"Going forward, the growth will slow down and ramp-up costs will decrease, in line with Norwegian's strategy," it said in a statement today. 

Operating profit before leasing and depreciation (EBITDAR) rose to 1.61 billion crowns from 990 million crowns a year ago. This was far above the average forecast of 916 million crowns. 

Norwegian Air has in recent weeks rebuffed takeover advances by Aer Lingus-owner IAG. It did not say anything new about the process today. 

The airline's shares have gained 26 percent since the start of the year, mostly due to IAG's interest in the company.