LONDON, March 28 (Reuters) - Britain's competition

regulator said on Thursday that it has decided not to open an

in-depth 'phase 2' investigation into Aviva's acquisition

of AIG Life UK.

Britain's Aviva agreed last September to buy the UK life

insurance business of U.S. insurer AIG, known as AIG Life UK,

for 460 million pounds ($580.43 million).

The transaction was expected to add 1.3 million individual

protection customers and 1.4 million group protection members to

Aviva's business, the UK insurer said at the time.

"The Competition and Markets Authority has decided, on the

information currently available to it, not to refer the above

merger to a phase 2 investigation under the provisions of the

Enterprise Act 2002," the regulator said in a statement.

($1 = 0.7925 pounds)