Credit Suisse is following similar moves by Citigroup, Merrill Lynch and Morgan Stanley, betting on a big expansion in carbon trading if, as expected, the United States launches a national carbon trading scheme after President George W. Bush leaves office.

In addition, many companies want to exploit a booming, unregulated trade outside Kyoto, for companies and individuals who want to offset their emissions, for example from flights.

"(Our goals) include rapid developments in the US and voluntary markets," said Bruce Usher, CEO of EcoSecurities.

"The carbon markets are growing rapidly."

Credit Suisse is paying 44 million euros for its stake, and EcoSecurities President Pedro Costa and Director Marc Stuart are likely to be major beneficiaries, holding up to now a 28 percent stake in the company.

As with all carbon project developers, EcoSecurities is helping generate emissions reductions in developing countries, called carbon credits, the vast majority of which haven't happened yet. As such the firm has very little revenue but high cash requirements to pay its 246 employees.

It also needs money to expand in the US

A cross-party climate change bill that aims to establish a national carbon trading scheme, supported by all the main presidential candidates, is before a US Senate committee.

By investing, Credit Suisse is betting that the Kyoto Protocol gets a new lease of life after 2012, when the present rich country commitments that drive the carbon market expire.

"Credit Suisse will not be investing if it thinks Kyoto will drop dead after 2012," said one analyst.

Other banks taking staking in carbon project developers so far this year include Merrill Lynch, in the Russian Carbon Fund, Citigroup, in UK-based Sindicatum Carbon Capital, and Morgan Stanley in Miami-based MGM International.

Credit Suisse will buy 9.2 million shares at 320p per share, a discount to EcoSecurities' Friday share price of 366-1/2p. EcoSecurities also said it would seek third-party financing for projects through Credit Suisse's clients.