NEW DELHI (Reuters) - A Dubai-bound Emirates flight was delayed at the Mumbai airport by several hours on Sunday morning after airport officials received a security alert, a spokesman for the Mumbai International Airport said. The flight, which had 356 people on board including crew, was preparing to take off from the runway but was called back after the air traffic control alerted the pilot of a potential security hazard from a passenger on board, the spokesman said. The flight was taken to the parking bay and all passengers were subjected to further security checks, he said. All of them have reboarded except two who have been held back for further checks, he said, adding that the flight was set to take off shortly. India has tightened security across its major airports in recent weeks after getting intelligence about a plane hijack threat from militants.