Canadian prime minister Paul Martin has rejected a call by US president George Bush to return to the negotiating table over the ongoing softwood lumber dispute.

The two leaders aired their views on the dispute, which involves America imposing hefty duties on imported Canadian softwood, during a 20 minute telephone conversation.

Mr Martin told Mr Bush there was no need to negotiate when Canada’s case had already been proved during a recent decision by a North American Free Trade Agreement panel.

He also hinted that Canada would now pursue matters in US courts to highlight its view that the US was in violation of an international agreement and its own domestic laws.

Canada has paid out some C$4bn in duties since they were introduced in 2002.