A strong performance from B&Q helped DIY retailer Kingfisher post a sharp rise in pre-tax profits in the half year to August 1.Pre-tax profits for the period came in at £201m, compared with £146m over the same period the previous year as revenues climbed 7.3% to £5.5bn from £5.1bn. Revenues were up by 1.4% excluding the impact of currency movements.The firm kept its interim dividend at 1.925p.UK-based DIY retailer B&Q, which accounts for about 40% of turnover, saw profits climb by 66% to £137m, Kingfisher said, with the chain benefiting from sales growth and continued margin and cost improvements.Sales and profits in France, where it operates Castorama, held flat in a weaker environment, the firm said. It said it saw continued strong growth in Poland, stabilized losses in China and resilient trading in Russia, Turkey and Spain.Kingfisher said it was helped by store revamps as part of a 'self-help' plan, which it managed to do at a price of £1m a store, compared to £2.5m previously. Margins were boosted by the closure of distribution centres. 'Looking forward, given widespread economic uncertainty, we continue to plan for challenging times,' said chief executive Ian Cheshire. 'However, we will retain flexibility in our trading plans and stay focused on our self help initiatives so that while managing the business tightly we can capitalise on better demand as it arises.'