Confusion arose after many NOCs registered all athletes who held the minimum qualification record following the June 29 deadline rather than just those included in the Pan American ranking system.

This led to a number of over 900 believing they had qualified, so over 200 hundred greater than the limit agreed with Games organisers, a situation described as "completely unmanageable" on a logistical basis.

In the last week, letters have been sent to each of the participating NOCs by Pan American Sports Organization President Julio Maglione highlighting the problem and how a Working Group had been convened to deal with the situation.

He accused the Association of Pan American Athletics of "total and absolute responsibility" for the problems.

All NOCs were urged to send "priority cases" of athletes who had been overlooked, with these then considered on an individual basis before the list was whittled down to an extra 31 following last night's PASO Executive Board meeting,

This means a total of 711 athletes will now compete.

However, the issues provoked fierce debate here at today's PASO General Assembly, with a delegate from the Cayman Islands claiming the situation is "unfair and unacceptable".

Smaller NOCs have been hit particularly hard, especially those from the Caribbean where athletics is by far their strongest sport on the programme. 

After a lengthy explanation from PASO Technical Committee head Michael Fennell, several suggestions were made.

Officials said that, with athletics competition only due to begin on July 19, nine days after the Opening Ceremony, spaces for additional athletes could be found due to the completion of several other sports.

But, after lengthy explanations of the practical difficulties of adding even more athletes, NOCs were urged to address their remaining concerns to Fennell and the athletics body.

In his opening address, Maglione, who assumed the Presidency on an interim basis following the death of Mario Vázquez Raña in January, admitted there has been a lack of "clarity and precision regarding the selection of athletes for the athletics sports that must participated in the Pan American Games".

He added: "It's evident that the absence of proper and timely information from the Association of Pan American Athletics has generated confusion; displeasure and what's worst, athletics who were already registered and had the illusion to take part in the Pan American Games have been affected.

"This negative experience must constitute, besides, a lesson to be taken into account for the next Pan American Games."

Exact details of the 31 extra athletes remain hazy, but it is clear that some of the 40 PASO members will not have an extra one. 

But although many of the continents biggest athletics stars will be absent, a strong field is expected nonetheless.

An 86-strong US team is set to be led by Olympic pole vault champion Jennifer Suhr, with two additional athletes, in men's 3000m steeplechase and women's 5,000m, to be added.

Star sprinters Kerron Stewart and Sherone Simpson are included in the Jamaican team, although details of any additions are yet to be circulated.