Johan Bohman, the secretive billionaire and shareholder in one of Switzerland's most exclusive private banks, is behind the investment vehicle that is financing XG Technology's plan to build a mobile network based on new technology in the US.

Aim-listed XG said that the little-known investment vehicle, called Treco International, would be XG's exclusive infrastructure partner in the US.

Treco described itself as having "many years of experience backing successful entrepreneurial ventures and are in a unique capital position, free from external financing for any present or future obligation". Mr Bohman is the ultimate beneficiary of Treco.

By renting equipment such as regional internet service providers and local telecommunications carriers to XG's customers, it in effect provided XG with the financial assistance to roll out its network and specifically designed handsets.

US-based XG's ambitious plans aim to undercut the existing US mobile network operators with its newly invented xMax technology that, in combination with VoIP, makes more efficient use of radio spectrum. As a result, it said its technology would be cheaper for would-be mobile operators than existing wide-area wireless technologies such as 3G or WiMax, as well as offering superior battery performance. However, critics have questioned its commercial and technical viability.

The announcement followed on from another deal in late September, in which Treco placed an order from XG for 1,000 base stations for $75m with the option for another 4,000, with an additional value of $300m.

High hopes for XG saw it make one of Aim's more explosive debuts in November 2006. Floating at $4.50, the shares soared to $14.60 in three months, valuing it at $1.8bn (£907m).

XG expects to roll out its system next month in the southern Florida market, followed by other US states. Initially voice service, data and modem services would be added on early in 2009, XG said.

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Secretive financier backing deal

The 45-year-old Johan Bohman is publicity averse and has kept a low profile throughout his career.

Nevertheless, he is well connected within the Swedish private equity market. A Swedish citizen who has lived in London since 1999, he graduated from the Stockholm School of Economics, specialising in Financial Theory, and in 1989, with Tomas Federer, began developing Investment Banking Partners, which became IBP Fondkommission. The group was the founder of the over-the-counter structured financial instruments markets in Scandinavia for institutional investors.

It was bought in 2001 by Switzerland's EFG Private Bank, part of EFG International, for an undisclosed consideration.

Besides founding Treco, he also has investments in the finance and real estate industries, building a real estate portfolio in Scandinavia and Germany.