Airports across India were put on high alert Sunday following a warning that a plane flying to Europe or the United States could be hijacked, news reports said. A US Internet center received an e-mail saying there were plans to hijack a US or Europe-bound flight from India, CNN-IBN television reported. The center handed the e-mail to the FBI which informed Indian intelligence, CNN-IBN television reported. The report did not say who sent the e-mail or if any particular airport or airline was at risk. It did not explain what an Internet center is. The Press Trust of India news agency citing unnamed officials said the risk was greatest in the southern city of Chennai. Security Commissioner S. R. Mehra told the television station that security measures at airports have been tightened as a result. "Travel is absolutely safe. There could some delays though," Mehra said. Police erected barricades on roads leading to airports in major cities including New Delhi, Mumbai, Bangalore and Chennai, the reports said. Airport officials in New Delhi declined to comment to the Associated Press about the reports.