By John Crawley WASHINGTON, March 14 (Reuters) - U.S. investigators have concluded that the crash of an EgyptAir (EGY) jetliner more than two years ago in the Atlantic likely was due to the actions of the plane's co-pilot, not mechanical or other problems, aviation sources said on Thursday. The final report on the probable cause of the crash, due to be released in the next few days by the National Transportation Safety Board, determined that co-pilot Gamiel El Batouty caused the Boeing 767-366 ER (BA) to crash off the Massachusetts coast on Oct. 31, 1999. All 217 people aboard Flight 990 from New York to Cairo were killed. EgyptAir and Egyptian investigators steadfastly have rejected that one of the crew would have brought down the plane. They have pressed U.S. investigators on possible mechanical problems, particularly with the 767's flight-control system. Sources who asked not to be named said board members wrestled over whether to conclude that El Batouty acted deliberately, and apparently left out that language from the report. They included the findings of Egyptian investigators as a counterweight that suggested mechanical problems were to blame, the sources said. A spokesman for EgyptAir had no comment on the board's final conclusions. The investigation proved to be politically charged and diplomatically sensitive. Egyptian government officials pressed their point in person with safety board members during the probe, and contacts were made about the case at the highest levels of both governments. NO SAFETY OR MECHANICAL ISSUES U.S. investigators concluded what they have said previously -- that there were no safety or mechanical issues with the aircraft that were related to the crash, two sources said. A number of tests, some requested by Egyptian investigators, were conducted at Boeing facilities in Seattle on data related to the plane's elevator systems as well as potential crash scenarios. Elevators are panels, or flaps, on the tail's flight-control system that def lect vertically to control the up and down movement of the aircraft's nose. There have been some reports of elevator problems on some 767 series aircraft, and the U.S. Federal Aviation Administration ordered a round of inspections last March. An official at Boeing had no comment on the safety board's investigation. The cockpit voice recorder, retrieved after the crash, showed that El Batouty was alone in the cockpit at the time the plane began its fatal plunge into the ocean, and that he repeatedly uttered in Arabic the words, "I rely on God," as the plane rapidly descended. The voice recorder also revealed that the pilot, Mahmoud el-Habashy, said "Pull with me!" several times in what was believed to be a desperate attempt to get the plane under control. The last contact with the plane was about three minutes before the crash, a routine transmission on air traffic procedures. There was no indication of any problem aboard the aircraft. ©2002 Reuters Limited.