Travelers Cos Inc, the top writer of commercial auto and business insurance policies, said on Thursday that third-quarter profit rose 15 percent, helped by strong underwriting results.

Earnings increased to $1.2 billion, or $1.81 per diluted share, up from $1.04 billion, or $1.47 per share, a year earlier.

St. Paul, Minnesota-based Travelers said operating earnings, which analysts use to measure performance, rose to $1.2 billion, or $1.81 per share, from $1.04 billion, or $1.46 per share.

Analysts on average had expected the insurer to earn $1.49 a share on an operating basis, according to Reuters Estimates.

In the year-ago quarter, the property and casualty insurer earned $1.04 billion or $1.46 a share from operations.

Travelers also raised its full-year 2007 outlook to between $6.52 per share and $6.62 per share from a previous range of $5.80 to $6.05, compared with Reuters Estimates' forecast of $6.24 per share.

So far this year, Travelers has fallen 4.3 percent compared with a 3.2 percent drop in the Standard & Poor's insurance index. (Reporting by Ed Leefeldt and Christian Plumb, editing by Gerald E. McCormick)