The move comes as two Canadian timber industry groups, who are opposed to the deal, launch lawsuits aimed at reviving the long-running legal tussle between the two countries.

Susan Schwab, deputy US trade representative, told a senate finance committee hearing that the details of the softwood agreement would be finalised “within the next few weeks”.

The agreement would end American duties on Canadian softwood lumber imports to the US, with US$4m in duties already collected being returned to Canadian timber companies. Canada’s share of the US softwood market would be capped at 34%.

Meanwhile, the Ontario Lumber Manufacturers’ Association and Ontario Forest Industries Association are taking action against the US government in the US Court of Appeals and the Court of International Trade in a bid to force the completion of a trade panel review case.

A North American Free Trade Agreement panel had been due to complete its review of key allegations in the dispute when the deal was announced. Both countries agreed to suspend the case and appoint panellists.

Canada had expected the panel to back its main assertion – that its lumber exports to America are not unfairly subsidised.