The former head of the World Trade Organisation Pascal Lamy predicts agreement will be reached on the Trans Pacific Partnership trade talks this weekend, but says the significance of the deal has been over-hyped.

The Frenchman who retired as WTO director in 2009 told The Australian Financial Review on Thursday on the fringes of the Boao Forum for Asia, that the importance for the world economy of the TPP would be "relatively modest".

With trade ministers of 12 countries including Australia's Andrew Robb trying to reach a deal this weekend at talks in Hawaii on cutting trade barriers, Mr Lamy said, "It's probably not worth the full-blown trumpets claiming it is the first 21st century trade agreement".

Pascal Lamy says the importance for the world economy of the TPP would be "relatively modest". Michele Mossop

The talks were supposed to set new modern standards in trade for fair competition between state-owned enterprises and private firms and for protection of foreign investment, but Mr Lamy said the countries in the TPP were so diverse and at such different levels of development that the "lowest common denominator will not be very high".

He said the other reason he was pessimistic was that the United States was not giving any sign it was willing to make major concessions itself in order to extract concessions from the other countries.