Lawyers for five plaintiffs whose next of kin were on board the ill-fated MH370 flight that disappeared four years ago have today sent a letter to Transport Minister Anthony Loke seeking his help to declassify several documents regarding the incident.

This follows an application made for discovery of these documents in a civil suit, and the subsequent response that some of the documents had been classified under the Official Secrets Act 1972.

The application had been filed by the firm of Ngeow and Tan along with their counsel Sangeet Kaur Deo to Loke.

They are representing the family of three passengers aboard the plane - Tan Ah Meng, 46, his wife Cindy Chuang, 45, and their eldest son, Tan Wei Chew. 16.

"While we received some documents following our discovery application, an affidavit affirmed by the Department of Civil Aviation (DCA) director-general states several material documents cannot be given to us as it is classified under OSA," the letter to the minister states.

The classified documents include the recording or transcripts of communication with MH370, letter of agreement of search-and-rescue operations between Singapore, Thailand and Indonesia, minutes of meetings held by the various agencies, internal memos, and the search-and-rescue report.

"The documents are vital to ensure the court knows the details of the final communication and the search-and-rescue operations done. It is imperative there is a full and frank exposure since it involves the lives of 200 people which is not explainable," the letter states further.

Following that, they hoped that the documents could be declassified.

The letter further said that should the DCA and others decline to declassify the documents, the reasons behind such decisions should be explained.

They added that they are also prepared to meet with Loke if he requires further clarification. The family further said the application for discovery is scheduled for hearing on Aug 3.

It was previously reported that last year they had sought a Federal Court ruling for the airline’s company, Malaysia Airlines Bhd - the new incarnation of Malaysia Airlines System Bhd (MAS) - to be cited as defendants.

Besides the five, there are many others including foreigners who have filed civil suits following the mysterious disappearance of the aircraft and its passengers and crew.

This includes the suit filed by the firm of Tommy Thomas, which represents more than 30 of the victims’ families.