San Luis were due to face Uruguayan outfit Nacional and Guadalajara were scheduled to take on Sao Paulo of Brazil.

Nacional and Sao Paulo earlier announced that they would not travel to Mexico as requested by the South American Football Confederation.

And Mexican Football Federation (FMF) president Justino Compean announced in a press conference that both sides had decided not to take any further part in the competition.

"We are notifying the South American Football Confederation (CONMEBOL) that we are not going to take part any more. We do not accept playing only one game or changing the venue. We only accept that the regulations have to be obeyed," said Compean.

"We are going to ask them to reimburse the Mexican sides financially. This decision, which is endorsed by us, is, I believe, the correct one and I do not think that it will affect us in the future."

FMF general secretary Decio de Maria added: "We are not interested in reprisals or fighting with anybody. We just respect the rules. We have to sit down with CONMEBOL's authorities and state our position.

"We want to stress that we decided to retire based on the rules."

CONMEBOL had hoped to find alternative venues for both round-of-16 matches which were postponed after the swine flu outbreak in Mexico.

But after Colombia and Chile refused to host the games, the South American authorities said the games would be played in Mexico if all teams agreed.

But safety fears meant neither Nacional nor Sao Paulo could be persuaded to travel to Central America.

A statement from the Nacional board said: "During an extraordinary meeting, we received a fax from the Mexican FA giving guarantees that it was safe to play in that country.

"The fax stressed that this weekend the domestic league was going to re tart with open doors to the fans.

"However, after listening to our health experts, we were advised not to play there as the virus has still not disappeared."

Sao Paulo manager Joao Paulo de Jesus Lopes insisted to Jovem Pam radio station that they would not fly to Mexico, adding: "It is irresponsible to play there."

San Luis president Eduardo del Villar had served notice of the team's intention to withdraw if Nacional refused to travel.

He added: "If they refuse to come we are going to retire from the tournament and then appeal to FIFA or any other body so they can be withdrawn of the competition as the rules say with a 3-0 defeat.

"The World Health Organisation says it is ok to play the games so everything they say is just an excuse."