Kent Reliance Building Society is poised to become a bank if savers and borrowers back plans for a multi-million pound cash injection and change of name.

The 150-year old Chatham-based mutual is in talks with private equity firm JC Flowers about a £100m joint venture, with each side pumping in £50m. It would create a new bank-style operation, although run by a mutual organisation owned by members.

The talks, which were confirmed today by Kent Reliance, have been prompted by pressure from the Financial Services Authority for building societies to have stronger balance sheets.

Building societies like Kent Reliance - sponsor of Charlton Athletic and former sponsor of Gillingham Football Club - have also faced intense competition from the taxpayer-funded banks like Northern Rock and Lloyds TSB. It has also had to pay into a compensation scheme to support failing financial institutions.

This has meant that the society, which employs some 50 people in Sun Pier, and hundreds in processing centres in India, has faced a slow-down in growth after years of being the UK's fastest-growing building society.

According to sources close to the society, the move would enable the organisation, to be known as KRBS and without the words "building society," to double in size over the next five years.

If approved, the move could pave the way for KRBS to expand by taking over smaller societies. This in turn could create new jobs in Medway. JC Flowers is also understood to want Kent Reliance to open new branches. Full details of the new structure will be revealed later this week.

There is also the possibility that when JC Flowers sells its stake, possibly in five to seven years; time, the society's 180,000 members could be in line for a windfall.

In a statement, Kent Reliance confirmed it was in talks with JC Flowers "to secure a substantial equity investment in the business which is subject to approval by members and we will be making a further comment in due course."

Members will vote on the proposal later in the year, with a Yes vote heralding the launch of the KRBS bank probably in the new year.