CORRECTED - AIG says to lay off about 605 workers after buyout

(Fixes number of job cuts in headline, 1st paragraphs)

NEW YORK, Sept 27 (Reuters) - American International Group Inc (AIG.N), the world's top insurer by market value, said on Thursday it plans to lay off about 605 workers following its takeover of auto insurer 21st Century Insurance Group.

The job cuts will take place over a period of two years, said Joe Norton, a spokesman for AIG, which earlier said it had completed the acquisition of 21st Century.

AIG said it expects to cut about 11 percent of the combined workforce of 21st Century and AIG's direct personal auto insurance business. Those two businesses employ about 5,500 people, Norton said.

(Reporting by Christian Plumb)