Veteran diplomat Tony Kemal Siddique died on Friday night of a heart attack.

He was 80, and was most recently Plenipotentiary Representative to the Caribbean Community.

Mr Siddique leaves behind his wife Sharon, their daughters Sophia and Samira, and two granddaughters, Misha and Roxy.

He previously served as Special Envoy for Arctic Affairs, and was Singapore's ambassador to a host of European countries, including Finland, Hungary, Italy, Norway, Sweden and Greece.

After retiring from the civil service in 1996, he went into the private sector and founded a strategic advisory firm, where he was executive director.

Mr Bilahari Kausikan, chairman of the Middle East Institute, remembers Mr Siddique as a "legendary foreign service officer" and an "operator par excellence", from whom a generation of diplomats learnt their craft.

Former president SR Nathan - who was then permanent secretary for foreign affairs - would appoint Mr Siddique when he "needed the impossible done", said Mr Kausikan.

For instance, Mr Siddique was key to raising the Cambodia vote at the United Nations (UN) in the critical first years of the 1980s after Vietnam's invasion, said Mr Kausikan, former permanent secretary for foreign affairs from 2010 to 2013.

Mr Siddique succeeded in lobbying for the coalition government of Democratic Kampuchea to retain Cambodia's UN seat, even though the odds were stacked against him.

"In the 2000s, he single-handedly got us observer status in the Arctic Council," he added. Singapore is the only small island observer state in the Arctic Council.

Professor Chan Heng Chee, who is also Ambassador-at-Large, said: "You could send Tony into very difficult situations and he can extricate himself and come out unscathed. He delivers."

Many of Mr Siddique's colleagues also remember him for his extraordinary talent at networking.

Veteran diplomat Verghese Mathews, who was Singapore's former Non-Resident High Commissioner to the Republic of Fiji, said: "Tony was a larger-than-life personality. Whenever he was present, he would invariably be the centre of attention and lead the conversation."

Mr Siddique was also generous with younger diplomats, showing them the ropes on how to write political briefs and interact with their foreign counterparts, said Ambassador-at-Large Ong Keng Yong.

"He taught us how there will always be private chit-chat and deal making on the sidelines, and we must always stay alert to counter those moves," said Mr Ong.

Mr Siddique was buried at the Choa Chu Kang Muslim Cemetery yesterday afternoon.