With British telecom giant Vodafone raising its ante in its bid to acquire Hutch-Essar and discussions intensifying in two other rival camps - Essar Group and Reliance Communications, private equity firms' interest in the deal has started waning, a report said.

Private equity buy-out firms involved in the keenly contested bid for India's fourth largest mobile player believe that they would not participate in any deal that valued Hutch-Essar much above $15 billion, British daily Financial Times reported on Wednesday.

The private equity interest in the takeover battle for Hutchison Essar has waned following the rapid escalation in its valuation, the report quoted unnamed people familiar with the situation as saying.

A small stake in Hutchison Essar was sold last year that valued the venture at $10 billion, while analysts last month estimated the company's enterprise value had risen to $14 billion, FT said.

However, Vodafone has flagged a potential offer of at least $17 billion, it added.

Among the private equity groups in talks to join a Reliance-led bid for Hutchison Essar are Blackstone, KKR, Carlyle and Texas Pacific Group.