An Asiana Airlines passenger jet continued flying for four hours after a warning signal appeared telling pilots that something was wrong with the engine.

According to the Ministry of Land, Infrastructure and Transport, the plane took off from Incheon International Airport at 8:50 a.m. on April 19 with 242 passengers heading for Saipan. About an hour after takeoff, a warning light appeared on the dashboard pointing to a problem with the oil filter in the left engine.

The pilot slowed down and took other measures, but the signal did not disappear. But the pilot and flight control at Asiana decided to keep flying as there were no problems with engine pressure or oil levels. The aircraft flew another four hours and landed safely in Saipan.

An inspection following the flight revealed an above-normal level of iron filings in the engine oil, requiring the problematic engine to be replaced.

"Regulations require necessary steps to be taken when a warning signal appears pointing to problems with the oil filter, and an aircraft must return if the warning signal does not disappear," a ministry official said. "Asiana ignored [these rules] and continued flying."

The carrier apparently told the ministry that the warning signal had disappeared, but the official said a thorough inspection later revealed that it had not gone away.

April 19 was just a few days after the ferry Sewol sank off the southwestern coast of Korea, leading to a massive death toll because the crew and owners flouted all safety rules.

The ministry official said Asiana committed another act that seriously endangered the lives of passengers, less than a year after one of its jets crashed during landing in San Francisco in July 2013. The official warned Asiana faces "severe punishment" according to the law.

The ministry plans to convene a disciplinary meeting next month and decide whether to suspend the pilot for a month, halt Asiana flights to Saipan for a week or slap the carrier with a W10 million fine (US$1=W1,041).

An Asiana spokesman said the carrier will "humbly accept" the decision and cooperate with the investigation. However, Asiana denied lying to the ministry and claimed there was a "miscommunication" between the pilot and flight control.

