Severn Trent has risked the collapse of a potential takeover after the British water company rejected a third bid from a consortium of investors.

LongRiver Partners - a consortium including the Kuwait Investment Office, the UK Universities Superannuation Scheme, and Canadian firm Borealis Infrastructure - saw its latest bid of £22 a share, which valued Severn Trent at £5.25bn ($8.14bn, €6.18bn), knocked back by the board.

Michael Rolland, president and CEO of Borealis, said on behalf of the consortium that the Severn Trent board had shown "no interest" in discussing the latest offer.

"Since we submitted our proposal on 14 May, 2013, no member of the consortium or its advisers has met any of the directors of Severn Trent or its advisers, despite repeated requests," said Rolland.

"In the absence of any such engagement, there will be no further proposal from the consortium and no offer for Severn Trent shareholders to consider."

LongRiver now has until 11 June to make a new offer, or shut down its takeover bid.

Severn Trent bosses rejected the last bid, claiming it did not reflecting the firm's long-term value. The utility company reported a 37% rise in annual profit in 2012/13 to £215m, and increased its dividend 8.2% to 75.85p.

"Throughout this process the Board has been careful to act in the best interest of shareholders. We have held private conversations with LongRiver and made clear that we have no objections to fuller discussions in the event that LongRiver puts forward a proposal which properly reflects the long term value and future potential of Severn Trent," said Andrew Duff, chairman of Severn Trent.

"The Severn Trent board has carefully considered this proposal. The board unanimously believes that this proposal is not at a level that adequately compensates our existing shareholders for selling Severn Trent's increasingly rare combination of yield, inflation-linked business model and record of operational delivery for customers."

Severn Trent has around 7.7 million customers across Wales, and central and western England.

The firm's share price dropped by as much as 5% in early trading on the London Stock Exchange, as the threat of LongRiver walking away from its takeover attempt looms overhead.