Lamy's entire first term has been dominated by the WTO's Doha round, launched seven years ago in the Qatari capital.

In a letter to the chairman of the WTO General Council, Bruce Gosper, he said that concluding the Doha round would go a long way towards establishing a multilateral trading system and ensuring that opening up trade would serve developing countries -- goals Lamy said he would fight for when he took the job.

"I would hereby like to notify you of my decision to seek reappointment as Director-General of the World Trade Organization for a further term upon the expiry of the current one on 31 August 2009," he said in the letter, a copy of which was obtained by Reuters.

Brazil's Foreign Minister, Celso Amorim, himself frequently tipped as a future head of the WTO, said he had encouraged Lamy to run again.

"I think he's a great asset for the organization. He is someone who has shown fairness, understanding, courage but at the same time equilibrium, so he has the qualities to continue to steer this ship," he told reporters after meeting Lamy earlier on Tuesday.