SAFETY improvements in the offshore industry are a lasting memorial to the 167 people killed in the Piper Alpha disaster, the Prime Minister has said.

In a letter to Malcolm Webb, chief executive of industry group Oil & Gas UK, David Cameron said the 25th anniversary of the deaths was a fitting moment to mark the skill, bravery and dedicated professionalism of offshore workers.

"The oil and gas industry is one of the UK's greatest industrial success stories. The sector has made – and will continue to make – a significant contribution to our country's economic prosperity," Mr Cameron wrote.

"Conditions in the North Sea are some of the harshest anywhere in the world. The work to provide the fuels we all rely on is a triumph of technical ingenuity and committed human endeavour.

"In this testing environment, the highest safety standards are paramount. I know how tirelessly the industry works to prevent incidents like Piper Alpha from ever happening again."

In the wake of the disaster, an inquiry led by Lord Cullen led to more than 100 changes to safety practice.

The Prime Minister wrote: "Over the past 25 years the North Sea has embraced continuous improvement in health and safety – an appropriate lasting memorial to those who suffered so terribly a quarter-of-a-century ago.

"We will never forget the 167 who lost their lives on July 6, 1988.

"And my thoughts as Aberdeen remembers its loss are with their families and loved ones, the survivors and all those involved on that tragic night."

The anniversary of the tragedy will be marked by a special commemoration service at the North Sea Memorial in Aberdeen.

The service, which is due to start at 11am, will begin after the flypast of an RAF Sea King helicopter from Lossiemouth. This was the first aircraft to arrive at the scene of the disaster 25 years ago.

First Minister Alex Salmond is expected to attend the service of remembrance and rededication which will be led by the Rev Gordon Craig, chaplain to the UK oil and gas industry.