The diplomat overseeing one of the most fractious areas of global free trade talks said he will leave his post in August, adding pressure on World Trade Organisation (WTO) member states to settle their differences before he goes.

The WTO's Doha round, launched in November 2001, has missed deadline after deadline because of many countries' reluctance to expose their firms and farmers to more foreign competition.

Don Stephenson, Canada's ambassador to the WTO since 2004, has for the past two years mediated talks over cutting tariffs on industrial goods such as cars, shoes, fuel and timber.

"My term as Canadian ambassador ends in August," Stephenson said on Friday, adding his last official duty as industry chairman would be a report to the WTO's 152-country membership "in the last few days of July."

His departure aligns with a critical moment for the Doha round, given WTO director-general Pascal Lamy has been pushing for trade ministers to meet before August to address the most politically-sensitive issues in the talks, such as the size of tariff and subsidy cuts on industrial and agricultural goods.

That would make it possible for an overall Doha deal to come together by the end of this year, before a new US administration enters the White House and creates uncertainty for negotiators.

Many developing countries have accused Stephenson of pushing them to open up their fledging industries too much, fearing job losses if their manufacturers cannot keep up with products imported from the US, Europe or China.

At the same time, wealthy nations have pushed for more business opportunities in emerging economies such as Brazil and India, and have called on Stephenson to seek deeper tariff cuts with fewer exceptions for sensitive industries.

Diplomats said Stephenson's departure was an added incentive to resolve the industry issues in the next two months.

"If the modalities package is done already, the Nama group doesn't become so pressing," one official said, using the trade acronym for industrial goods or Non-Agricultural Market Access (Nama).

"Nobody is thinking much past July." Stephenson's post - formerly held by Stephen Johannesson of Iceland and Pierre Louis Girard of Switzerland - is widely seen as thankless given the huge gaps between countries in the area.