U.S. climate envoy takes aim at developing nations

* Stern says developing countries' inaction "not helpful"

* Progress "too slow" on UN climate negotiating track

* Republicans continue boycott of Senate climate hearing

By Deborah Zabarenko and Richard Cowan

WASHINGTON, Nov 4 (Reuters) - The top U.S. diplomat on climate change took aim at developing countries on Wednesday, saying their inaction was not helping shape a global agreement to be considered in Copenhagen in December.

"The sooner we get past the pattern of resisting responsible action and the sooner we get into the pattern of searching for pragmatic common ground, the better off we will be," Todd Stern told a hearing of the U.S. House of Representatives Foreign Affairs Committee on Wednesday.

In uncharacteristically blunt language, Stern said progress on the formal U.N. climate negotiating track has been too slow, with just 32 days before the start of the international climate conference in Copenhagen.

Asked whether the United States would be able to sign on to a global agreement in Copenhagen, Stern said, "I think we have a fair distance yet to go but I actually think there is a deal to be done."

He told the committee that some developing countries are "hiding behind a misreading" of language in two key climate documents, the 1992 U.N. Framework Convention on Climate Change and the 2007 Bali Action Plan, which recognize different responsibilities and capabilities for rich and poor countries.