Amlin, Lloyd's of London biggest insurer, raised its interim dividend as it reported a 29% hike in first half pre-tax profit but cautioned that the upcoming hurricane season could increase claims payouts.The group said pre-tax profit increased to £177m in the six months ended 30 June from £137m a year earlier, helped by lower claims levels and as financial markets stabilised in the second quarter of 2009. The group, which makes around half of its premium revenue from the US, said gross written premium increased 33% to £950.1m from the same time a year before, boosted by the rising US dollar.An interim dividend of 6.5p has been recommended, up from 6p a share the year earlier.However, Amlin warned that the forthcoming US hurricane season could "materially impact its claims payouts in the second half of the year." The group added, "Amlin is well positioned to take advantage of more favourable market conditions with ample capital, superior ratings and a robust infrastructure. With this backdrop, the prospects for a strong return on equity for 2009 and 2010 are good."