Singapore and Indonesia on Friday moved to defuse a fresh diplomatic row over a 1965 bombing in the city-state, after the Indonesian navy dressed two marines as bombers at a defence exhibition.

The neighbours acted to mend relations after Singapore said it was "concerned and disappointed" by the appearance at the event in Jakarta of two men dressed as Indonesian marines Usman Haji Mohamed Ali and Harun Said, who were executed for the bombing.

Singapore said a delegation from its armed forces had pulled out of the Jakarta International Defence Dialogue exhibition on Wednesday after learning of the stunt while diplomats in Jakarta spoke with officials "to express disappointment".

Indonesia had already outraged Singapore last month by naming a newly refurbished navy frigate "Usman Harun" in honour of the marines, leading the ship to be banned from Singaporean ports and naval bases.

Three people were killed and 33 others injured in the bombing of MacDonald House in downtown Singapore in March 1965.

The attack was part of efforts by then-Indonesian president Sukarno to stage an armed confrontation against the newly formed federation of Malaysia, which included Singapore.

The two marines were executed in 1968 after being found guilty of carrying out the bombing at a trial.

Singapore Deputy Prime Minister Teo Chee Hean said in a statement Friday that Indonesian Coordinating Minister for Political, Legal and Security Affairs Djoko Suyanto had phoned him and "expressed regret over the inappropriate conduct by the soldiers".

Indonesian defence minister Purnomo Yusgiantoro also phoned his Singaporean counterpart Ng Eng Hen over the incident, according to the statement, while the Indonesian navy launched an investigation to find out who was responsible.

Both Teo and Coordinating Minister Suyanto "expressed their common desire to continue working together to have good bilateral relations," the statement said.

Indonesian navy spokesman Untung Suropati, speaking to AFP earlier Friday in Jakarta, described the two marines as "heroes" who should serve as role models for young Indonesians.

"Usman and Harun are our heroes, and it was an international expo with a young generation of the military and students visiting," he told AFP in Jakarta.

He added that when the navy designed the booth, they were not aware that Singapore would be attending the conference.

Relations between Singapore and Indonesia hit a low point in the late 1990s after the fall of former dictator Suharto, and his successor B.J. Habibie famously referred to the city-state as a "little red dot" on the map.

But ties have improved considerably in recent years, and Indonesia is now Singapore's third-largest trading partner.

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