Under a plan announced on Wednesday, Washington said it would grant up to 24,000 Venezuelans humanitarian access to the United States by air, while enabling U.S. officials to expel to Mexico those caught trying to cross illegally by land.Register now for FREE unlimited access to Reuters.comThe Mexican government's National Migration Institute (INM said it would be in permanent communication with U.S. border authorities, and warned Venezuelans planning to take advantage of the scheme to enter the United States not to form caravans.On Saturday, INM officials backed by the National Guard broke up migrant groups trying to move from the southern border state of Chiapas into neighboring Oaxaca, where Venezuelans have been gathering to obtain transit permits, an INM source said.To qualify for the U.S. program, Venezuelans will need to be able to secure a sponsor in the United States in advance.Mexico's government had already instructed Venezuelans not to proceed to the U.S. border before making their applications."