At least 70 Argentine police officers on duty at a regional summit to be attended by US President George W Bush have suffered food poisoning.
Thousands of police have been deployed for the summit
They all ate lasagne at a hotel in the resort town of Mar del Plata. The officers were briefly taken to hospital and were given time off to recover.
The police were among more than 8,000 officers guarding the summit.
Left-wing groups have announced protests against Mr Bush on Friday - but said they would be peaceful.
Argentine Interior Minister Anibal Fernandez has called for improvements in food safety monitoring at the venue.
He also suggested that the water the officers drank might have been the cause of the infection.