(AFP) Charges that Malaysia was a launchpad for the Sept 11 terror attacks on the United States were greeted with incredulity here today, but a key suspect is already in detention.

Prime Minister Mahathir Mohamad demanded proof of a reported secret FBI allegation that the Southeast Asian country was "a primary operational launchpad" for the attacks.

"As far as we know, there is no Malaysian connection in the attacks in the US," Mahathir told a news conference in response to a question about the FBI charge, which was carried in Newsweek magazine.

However, a chief suspect reportedly named by the FBI, former army captain Yazid Sufaat, is one of 23 alleged Islamic militants who have been detained under Malaysia's Internal Security Act in the past two months.

Police say they are members of a Malaysian Militant Group (KMM) which planned to topple the government, and have played down suggestions of a role in the US attacks.

"What we do know is that there are Malaysians who go to train in Pakistan and Afghanistan and have come back with the intention to destabilise this country," Mahathir said today.

Asked specifically about Yazid's alleged role, Mahathir said: "Let's see the evidence. It is very easy to say ... did he do it in Malaysia? Did he plan everything? I doubt it. It is too sophisticated an operation."

He said some individuals implicated in the US attacks might have come to Malaysia as tourists but authorities could not arrest them as they were not aware of their background or plans.

Key man

Newsweek said in its latest edition that US intelligence sources believe Yazid was a member of the Islamic extremist group Jemaah Islamiah and helped develop a support network for chief terror suspect Osama bin Laden in Malaysia and throughout Southeast Asia.

In January 2000, Yazid held a meeting in his Kuala Lumpur condominium with top associates of bin Laden in accordance with instructions given to him by an Indonesian cleric with ties to al-Qaeda, the Saudi dissident's terror network, the magazine reported.

Two of those in attendance - Khalid Almidhar and Nawaf Alhamzi - surfaced in the United States where they enrolled in flight school and later piloted the plane that struck the Pentagon, the report said.

Later in 2000, Yazid hosted French national of Moroccan descent Zacarias Moussaoui, the only man charged so far in connection with the Sept 11 attacks, according to the report.

Yazid gave Moussaoui letters of employment as "marketing consultant" for Infocus Tech, which were found in his Minneapolis apartment, and agreed to pay him US$2,500 a month during his stay in the US along with a lump sum of US$35,000 to get him started, Newsweek reported.

Biochemistry graduate

Last December, Malaysian investigators discovered that Yazid had ordered four tonnes of ammonium nitrate, a powerful explosive used in truck bombs, the magazine said.

Police here say Yazid, 38, a biochemistry graduate of California State University, was arrested on Dec 9.

The Newsweek report said Yazid was suspected of being a member of Jemaah Islamiah, accused by neighbouring Singapore of planning to bomb the US embassy and other Western targets in the island state.

Inspector-General of Police, Norian Mai, said last week that 19 of the 23 detainees had received military training outside the country - 10 in Afghanistan and nine in Mindanao in the southern Philippines.

"We see that they have links with Singapore, Indonesia and southern Philippines," he said, suggesting the groups together hoped to create "an Islamic region or an area ruled by their Islamic ways".

An ironic aspect of Mahathir's reluctance to accept Yazid's alleged role in the US attacks is that in the past his government has had to deny charges that it was simply using the Sept 11 attacks to crack down on domestic political opponents.