A U.N.-appointed expert panel says international efforts to encourage investment in green technologies could collapse if countries don't boost the market for 'climate credits.'

The United Nations Framework Convention on Climate Change says governments need to restore investors' faith in so-called carbon markets, including the U.N.'s Clean Development Mechanism.

The CDM allows developing countries to earn credits from measures to reduce greenhouse gas emissions. They can then sell the credits to rich nations seeking to meet emissions reduction targets.

But prices for climate credits have dropped recently because of uncertainty about countries' commitments to future emissions reduction.

The Bonn, Germany-based UNFCCC said Monday the CDM has helped cut about 1 billion tons of greenhouse gas emissions and resulted in huge investments to poor countries over the past decade.