PETALING JAYA (THE STAR/ASIA NEWS NETWORK) - Malaysian Prime Minister Najib Razak paid tribute on Saturday to former US envoy Jamaluddin Jarjis and 'Chief of Staff' Azlin Alias, who died in a helipcopter crash that killed all six people on board.

The helicopter crashed at a rubber plantation near Kampung Sungai Pening in Semenyih, Kajang, en route to Subang from Kuantan.

Tan Sri Jamaluddin Jarjis contributed much to Malaysia and played a vital role in strengthening Malaysia-America relations, said Datuk Seri Najib Tun Razak on Saturday, as he visited the crash site.

"I consider him to be a highly capable man who has done much for his party and the nation. When he was our Ambassador in Washington, he played a vital role in building relations with the United States and he shared his opinion and advice with me.

"His loss is a terrible tragedy to the nation, and I am very sad over what has happened."

Mr Jamaluddin was Malaysia's Ambassador to the United States from 2009 to 2012.

Mr Najib said Mr Jamaluddin's death was a great loss to him and his family.

"Jamaluddin was an old university friend of mine, and our political careers were closely intertwined," he said, adding that Mr Jamaluddin helped him as an adviser in the Prime Minister's Department.

Mr Najib also spoke of Datuk Seri Azlin Alias, private secretary at the Prime Minister's Office, saying they had a close working relationship when Mr Azlin was private secretary.

"He had agreed to leave his career in the corporate world to serve the government in a form of national service. Azlin was dedicated, trustworthy and liked by all. His death is a profound loss for me. He has helped me with many important government matters," said Mr Najib.

Mr Azlin was previously director of the Economics Division at the Prime Minister's Department.

Mr Najib said Mr Azlin and Mr Jamaluddin were examples to follow.

"We must follow their example so we can be more united and close ranks to continue our struggle and service to the nation," he said.

He added that the investigation into the crash would be thorough.

"The investigation must be done thoroughly and all aspects of the tragedy investigated completely to determine its cause. It is too early to come to any conclusion. A thorough and comprehensive investigation must be carried out as soon as possible so the cause of the crash is identified," said Mr Najib.