Ministers participating in the three-day informal meeting of the World Trade Organization wrapped up discussions Sunday but failed to narrow a huge gap over the controversial farm trade issue, further clouding the prospect of meeting a self-imposed March 31 deadline.

Ministers vowed to commit themselves to meeting the deadline for setting numerical targets on reductions of tariffs and subsidies, which remains "an awesome challenge," according to WTO spokesman Keith Rockwell.

Further negotiations are expected to take place in Geneva, but the Tokyo meeting is the last ministerial one before the March deadline.