In an unusual move to preserve safety and protect its reputation, national carrier Malaysian Airlines offered a M$100,000 ($205,000) reward to employees to unmask a 'traitor' within the ranks who has sabotaged four jets since October. The airline and police suspect a disgruntled employee is the saboteur but have not been able to identify a culprit. Scores of airline employees have been arrested, questioned and released without a single charge being laid. Police say the sabotage, all at the Kuala Lumpur International Airport, is not connected with terrorism. Security has been beefed up and new rules introduced to curb employee access to planes but the saboteur struck for the fourth time a fortnight ago, pouring corrosive hydraulic fluid on the cockpit dashboard of an Airbus 330 bound for Osaka. In all four cases, maintenance crews and pilots spotted the damage, easily giving rise to speculation that the saboteur wanted the damage discovered before flights took off. 'He or they are a serious threat to the company's business and a dangerous enemy within and a traitor to the country,' said airline managing director Ahmad Fuad Dahlan in a message to employees on Monday, offering the cash reward. 'Clearly this person's motive is to undermine the very principle of safety that we have all worked very hard to uphold. He is a serious threat to the company's business.' Officials said repairs were costly and damage to the airline's reputation was 'very disturbing'. 'Malaysian Airlines has one of the best airline safety records in the world and this traitor is undermining it,' an airline spokesman said. Last October, the saboteur cut cockpit wires on two Airbus 330 aircraft, one bound for Mumbai and the second on standby. In November, cockpit wires were cut on a Boeing 777 bound for Perth. In all cases the sabotage was discovered by maintenance crews and pilots well before departure.