As part of the agreement with Tanzania, Norway will support research, education and the development of pilot areas for reducing deforestation. Norway will also help develop ways to measure the amount of carbon captured by forests.

Norwegian Prime Minister Jens Stoltenberg said the agreement would make Tanzania an example for other countries of incorporating forests into fighting climate change.

"How to do it, and how to combine the idea of rural development with creating new sinks for carbon dioxide by planting new trees is exactly what we are going to do in Tanzania," he said in Dar es Salaam after the deal was signed.

His office estimated that emissions of greenhouse gases from Tanzanian deforestation -- at around 100 million tonnes a year -- were roughly twice as much as Norway's annual emissions. In terms of forest destruction, Tanzania was surpassed only by Sudan and Zambia, it said.

Norway has in the past reported slow progress in finding investments in developing countries which could cut production of the greenhouse gases blamed by many scientists for global warming.