Amlin's FY profit falls on lower investment return

* Pretax profit falls to 258.7 mln stg from 325.7 mln stg

* FY investment return down 26 percent to 118.5 mln stg

* Will pay special dividend of 15 pence per share (Adds details, analyst comment)

March 2 (Reuters) - British insurer and reinsurer Amlin Plc (LSE: AML.L - news) said its full-year pretax profit fell 21 percent, hurt by low interest rates and a fall in investment return.

The largest listed British underwriter, which underwrites property, casualty, marine and aviation insurance, said it was reorganising its business into three business units to improve its global presence.

Amlin's pretax profit fell to 258.7 million pounds in the year-ended Dec. 31, from 325.7 million pounds a year earlier.

Specialist insurers and reinsurers have been under pressure as low interest rates weigh on the premiums they can charge.

"Rate softening will be a drag on future earnings but as with a number of peers, Amlin is buying more reinsurance cover to reduce catastrophe exposure, which we think has positive valuation implications," Numis analysts said in a note to clients.

Numis cut its rating on the stock to "hold" from "buy".

Investment return fell 26 percent to 118.5 million pounds from a year earlier.

Amlin said it would pay a special dividend of 75 million pounds, equivalent to 15 pence per share and a final dividend of 27 pence per share, compared with 26 pence last year.

This is Amlin's first special dividend since 2006.

(Reporting by Aashika Jain in Bengaluru; Editing by Anupama Dwivedi)