MILAN, July 23 (Reuters) - Eni said on Tuesday

it signed an exclusivity agreement with investment firm KKR

over the potential sale of a 20%-25% stake in its

biofuel unit Enilive, based on a valuation of the company of up

to 12.5 billion euros ($13.6 billion).

"The strong interest shown in this period by leading

institutional financial investors could lead to the

subsequent sale of a further stake of up to 10% of Enilive," the

Italian energy group said in a statement.

($1 = 0.9185 euros)