''It is imperative that industrialised countries transfer clean technologies to developing countries at low cost or no cost,'' Nobel prize winning economist Joseph Stiglitz said here Saturday.

The issue of transferring green technologies, especially those under patent, has been plaguing global climate negotiations for years.

Asked how this could be sorted out, Stiglitz told IANS: "There must be compulsory licences for technology transfer, like the US did for some technologies after 9/11, and what has been done for life saving drugs."

Addressing journalists on the sidelines of the Feb 3-5 Delhi Sustainable Development Summit, Stiglitz said his suggestion did not mean that inventors would go unrewarded.

"They do get compensation. But for clean technologies, we must promote joint research efforts by governments."

He gave better batteries for electric cars as an example.

The Columbia University professor said: "The patent system creates a market failure, because everybody does not have the same information. Today, we are socialising losses and privatising gains. This is the result of legislation caused by lobbying."

Calling for an end to this system, Stiglitz recalled how BP could escape full liability for the Gulf of Mexico oil spill last year due to "faulty" laws.

As carbon dioxide is the main greenhouse gas causing global warming and leading to the problems associated with climate change, Stiglitz suggested "a high carbon price" that would force individuals, firms and governments to act more responsibly towards the environment.