A coroner was praised last night for striking a blow for public openness after he refused to return "highly sensitive" Ministry of Defence documents relating to the Nimrod spy plane crash in Afghanistan that killed 14 servicemen.

Andrew Walker, Oxfordshire assistant deputy coroner, also refused a request not to read the confidential documents after the MoD claimed it had released them in error.

His intervention marks the latest row over the UK Government's alleged reluctance to disclose information about the disaster which was the heaviest loss of life suffered by British forces in a single incident since the Falklands War.

The inquest has been delayed due to the RAF's failure to release the report of their Board of Inquiry, which found that ageing components and lack of fire suppressants were partly to blame for the crash in 2006.

Speaking at a pre-inquest hearing at the Oxford Coroner's Court yesterday, Mr Walker said he was concerned that, if he returned the documents, he would not see them again.

His stance won the praise of victims' families and MPs.

Angus Robertson MP, the SNP Westminster leader and defence spokesman whose Moray constituency is home to the Nimrod fleet, said: "This is clearly a serious blunder by the MoD, but if this information is relevant to the coroner's inquiry, then it must be considered, and that is a judgment that Mr Walker is best placed to make."

Graham Knight, whose son Ben was 25 when he died in the Nimrod disaster, said the latest argument fitted into a "pattern of non-disclosure" by the MoD.

Using freedom of information legislation and a series of leaked e-mails, Mr Knight, who attended yesterday's hearing, found that there had been 2496 safety incidents and it was known that Nimrods were prone to fuel leaks.

He said yesterday: "There has been a pattern going on for some time with the MoD when it comes to inquests of service personnel, they want coroners to know as little as possible."

The 37-year-old Nimrod XV230 came down in flames near Kandahar in September 2006 killing all the crew, 12 of whom were based at RAF Kinloss, Moray. It stunned the close-knit community of Kinloss. Flags flew at half-mast, flights at the base were grounded as a mark of respect and people laid flowers at the station gates.

David Evans, acting for the Ministry of Defence at the pre-inquest hearing, said the two documents, which were provided by a third party, should not have been released to the coroner.

He asked Mr Walker to send the documents back, unread, and said the MoD was confident that permission to return a "redacted" version would be granted.

Mr Walker replied: "My concern is that if I surrender these documents, I am not going to see them again. I am not going to return these documents, they were given to me lawfully."

He refused a request from Mr Evans not to read the documents.

The inquest is likely to start on May 6 following the completion of a further pre-inquest hearing.

A spokesman for the MoD denied that it had failed to disclose relevant documents.

He said: "For the safety of our personnel deployed on operations the material needs to be carefully considered before it can be used by the coroner in his investigation.

"It is our intention to provide the coroner with a redacted copy of this material."