Prime Minister Stephen Harper said Wednesday he is "disappointed" with the decision of the United States to impose 10 per cent duties on some imports of Canadian softwood lumber.

The duty will go on lumber from Ontario, Quebec, Manitoba and Saskatchewan.

An international tribunal in February found that Canada failed to properly calculate quotas on softwood lumber exports over the first half of 2007. The tribunal ordered Canada to remedy the breach by March 28.

Trade Minister Stockwell Day has offered a payment of $36.7 million US, but the Office of the United States Trade Representative claims it is owed $54.8 million US from the four provinces.

The duty is seen as a new test of the 2006 Softwood Lumber Agreement.

"We’re not disputing the ruling, but we would have preferred, obviously, the Americans wait to get these parts of the ruling that are unclear sorted out," Harper said in Moncton, N.B.

"We’ll continue to work to find some kind of resolution that’s satisfactory to the Americans, to our industry and also, of course, to the tribunal itself. But, I say, we need some greater clarity before proceeding ourselves."