TAIPEI, May 27 (Reuters) - Taiwan's largest air carrier China Airlines (2610) said on Monday its codesharing deal with Delta Air Lines (DAL) would still become effective June 1, but the ceremony marking the event would be postponed indefinitely. "The (codesharing) deal will proceed as planned, but we don't know when the ceremony can be rescheduled," China Airlines vice president Paul Wang said by telephone. The ceremony had originally been scheduled for May 31, but was postponed after a China Airlines plane broke apart in mid-air over the weekend and plunged into waters off Taiwan minutes after takeoff. It was the fourth major crash for China Airlines since 1994. China Airlines shares sank the seven percent daily maximum at the opening bell and remained there at 0227 GMT, while the main index (TWII) reversed an earlier sharp fall to rebound 0.22 percent to 5,718.96 points. ©2002 Reuters Limited.