Spirits giant Diageo today predicted a turnaround in its North American business, saying that sales in its most profitable market would grow in the second half of the year. 

The maker of Johnnie Walker scotch, Smirnoff vodka and Guinness has been struggling with weak performances for several quarters, especially in vodka due to a current preference for "brown spirits" such as bourbon and rum. 

The company is working to improve its performance by tweaking its business model to focus more on sales from wholesalers to retailers, rather than its shipments to wholesalers. 

The change has put pressure on sales in the near term but is designed to reduce industry inventories and better align the company's shipments with consumer demand. 

In the first half of its fiscal year which ended on December 31, Diageo's sales rose 1.8% on a like-for-like basis, slightly better than analysts were expecting. 

The company said its performance was hit by the weakness of several currencies, including the euro, the Venezuelan bolivar and the Brazilian real, against sterling.

North American sales fell 2%, in line with company expectations. They were hurt by the sale of assets such as Diageo's wine business as well as the timing of launches of new Ciroc vodka flavours. 

But North America "will be back to top-line growth in the second half," Diageo's new chief financial officer Kathryn Mikells said, adding that it had underperformed rivals in the region.

On a reported basis, Diageo said net sales fell 5% to £5.6 billion ($8 billion). Earnings per share came in at 56.1 pence. 

For the full year, Diageo repeated its goal for volume growth to drive stronger a top-line performance, with margins improving slightly. 

"I expect to see an overall improved top-line performance in the second half, led by shipment growth in US spirits," Mikells said. "Margin will come in roughly flat in the second half." 

Looking further ahead, Diageo reiterated that it expects revenue to increase by a mid single-digit rate from fiscal 2017.

Diageo noted today that Guinness sales were up 5% in Ireland over the six months to the end of December.

The company reported net global sales of the stout, one of Ireland's most significant exports, up 9% over the period. Guinness also saw strong growth in Nigeria, with sales there jumping by 28%.

Meanwhile, net sales of Baileys increased by 6%, mainly driven by growth in the UK and US.