Lloyd's of London insurer Amlin swung back to profit in the first half of 2012, helped by a sharp drop in catastrophe-related claims and higher premiums.

Amlin booked pretax profit of £184.5m in the six months to end-June today compared with a pretax loss of £192m a year earlier.

Its shares rose after the results announcement.

Bringing further cheer to investors, the group also said it had agreed a new five-year, unsecured £300m debt facility with its lenders, replacing a £250m loan that was due to mature in September 2013.

"This is a welcome return to profit and the strength of our underwriting result underlines the quality and diversity of our business," chief executive Charles Philipps said in a statement.

Global insurers suffered losses of $116 billion in 2011 after a slew of natural disasters including Japan's Tohoku earthquake led to a surge in claims.

Premiums have risen as a result and the absence of an earthquake, hurricane or flood of similar magnitude so far this year has helped stronger insurers to grab more market share at the expense of smaller rivals still grappling with last year's big payouts.

Amlin reported an underwriting profit of £153.8m, compared with a loss of £203.8m a year ago.

The group raised its half-year dividend by 4.2% to 7.5 pence per share.