Written by Professor Michael Leifer, who is now at the London School of Economics, the eight-page article confirmed that leaflets, which called on Malays to kill the Chinese, were distributed in Singapore prior to the bloody clashes.

The riots, which broke out on July 21, during religious celebrations on the Padang, resulted in 33 deaths and some 600 injuries. The leaflets, he said, were sponsored by the Singapore-Malay National Action Committee, a body set up earlier that year by United Malays National Organisation (Umno) members.

Entitled Communal Violence in Singapore, the 34-year-old piece reinforces the accuracy of SM's book which relates the merger and separation of the two countries.

The book has been the centre of controversy since its launch on SM's 75th birthday on Wednesday. Malaysian leaders have accused SM Lee of being insensitive for releasing his book while bilateral ties are at a low point.

In a radio interview with the British Broadcasting Corporation on Wednesday, Prof Leifer had said that Malaysia's response reinforces SM's point that Singapore is vulnerable in a predominantly Malay region.

He had pointed out that SM Lee's own account of the race riots was similar to his own, which he penned 34 years ago.

In it, he wrote: "There is reason to believe that prominent figures in Umno, including the secretary-general, have been actively engaged in a campaign of agitation among Malays in Singapore.

"It would probably be nearer to the truth to say that those activists were part of a deliberate design to embarrass, if not to remove, the Chinese-dominated People's Action Party government in Singapore which is regarded by many in Umno as a threat to Malay pre-eminence in Malaysia's political life.

"The dangerous consequences of playing communal politics are evidenced by Singapore's bloody days in July and September. An even greater danger is that at a time when the new Federation is facing the external menace of Indonesian 'confrontation', any exploitation of communal feeling, which could well spread, can only benefit Malaysia's enemies."

Relating the events of July 21, which was the anniversary of Prophet Muhammad's birthday, Prof Leifer said that more than 25,000 had attended a rally on the Padang.

They had gathered there in anticipation of a processional march to the All-Malaya Muslim Missionary Society premises in Geylang.

"It was noticed that among the crowd at the rally, about 30 men were dressed entirely in black and were wearing Malay warrior hats," he wrote. Upon reaching Geylang, these men provoked incidents with the Chinese who retaliated as the attacks increased. The clashes, which continued for several days despite immediate police action and curfews, were aggravated by Chinese secret society gangsters, he said.

He added: "Clearly, the explanation for these disorders does not lie solely in the religious celebrations which provided the occasion for their occurrence.

"The activities of Umno extremists did nothing to ameliorate racial tension already aggravated by Singapore's economic problems. Probably these elements were unable to conceive of any other weapon against the ambitions of Singapore's Prime Minister than the communal one."

"Meanwhile, Tunku Abdul Rahman had claimed that the Indonesians were behind the riots. Evidence on this score is by no means conclusive.

"However, one member of the Malay Action Committee has been described in a Federal Government publication as a 'close Indonesian agent' and it is also known that representatives were drawn from the socialist Pan Malayan Islamic Party, which has advocated union with Indonesia," he concluded.