(Adds detail, background) July 28 (Reuters) - Australia's Spark...

(Adds detail, background)

July 28 (Reuters) - Australia's Spark Infrastructure (SKI) received a sweetened buyout offer from a consortium including private equity firm KKR & Co Inc KKR.N that values the electricity infrastructure investor at A$5.04 billion ($3.71 billion).

The consortium, which also includes Ontario Teachers' Pension Plan Board, was now offering A$2.90 for every Spark share, up from its previous offer of A$2.80 apiece, at an 11.5% premium to Spark's last close.

Spark, which operates an electricity distribution network in Southern Australia, on Wednesday agreed to open its books to the consortium, just weeks after it denied due diligence and snubbed the previous bid, saying it was inadequate.

The offer comes amid a flurry of deals in Australia as record-low interest rates prompt institutional investors to chase higher yields. Spark has seen its share price rise more than 23% in 2021 as infrastructure spending and industrial activity rebound.

($1 = 1.3576 Australian dollars)