* G20 get 90 percent of clean investments; others lose out
* UNDP urges poor to take steps to promote green investment
By Alister Doyle, Environment Correspondent
OSLO, June 2 (Reuters) - Many developing nations are missing out on a surge in investments in clean energy and need to cut red tape and agree new rules to attract funds to help fight climate change, a U.N. finance guidebook said on Thursday.
