Bermuda-based insurer Catlin Group Ltd reported a 12 percent rise in gross premiums written in the first quarter, driven by strong growth in its property and casualty businesses.Catlin's casualty business was boosted by growth in US and international hubs as well as rate increases for marine liability, while property gross premiums written rose due to a strong international property business and selected rate increases following superstorm Sandy.The company posted gross premiums written of $1.84 billion, up 12 percent from the $1.64 billion the company reported last year. The firm said total gross premiums written by non-London underwriting hubs increased by 21 percent for the period and accounted for 58 percent of gross premiums written as opposed to 54 percent last year."We have made a very good start to the 2013 underwriting year,” Catlin’s chief executive officer Stephen Catlin said. "Premium rates have continued to rise in most classes of business, with the notable exception of the airline account."Gross premiums in the company’s casualty division were up 25 percent to $330 million, while property jumped by 23 percent to $158 million supported by international business and rate increases following Hurricane Sandy.Reinsurance climbed 15 percent to $903 million driven by volume in its continental European reinsurance hub, Catlin Re Switzerland, and growth in the US.Specialty war and political risks rose 2.0 percent to $161 million while energy and marine increased 1.0 percent to $214 million.Aerospace, however, fell 8.0 percent to $78 million as volume was affected by competitive pressure and delays in scheduled satellite launches.The company incurred no catastrophe losses in the quarter."Whilst the rest of the year may not be catastrophe-free as the first quarter was, we are optimistic that the global infrastructure that we have built over the past decade and our emphasis on capital preservation will continue to benefit our clients and shareholders alike. We look ahead with confidence," Mr Catlin said.Catlin's total investment return for the first three months of this year was $48 million or 0.5 percent compared with $47 million or 0.6 percent as of March 31, 2012. Investment return includes all mark-to-market adjustments.Total cash and investments came to $8.56 billion at the end of March, a 2.0 percent rise compared to the previous year’s $8.41 billion. Year-to-date total investment return came to 0.5 percent, down from 0.6 percent the prior year.Catlin shares closed at 538.00 pence on the London Stock Exchange on Friday. They have risen about 28 percent in the past year.