The investigation into terror groups in Southeast Asia widened Saturday as Malaysia announced the arrests of two more suspected militants tied to Al Qaeda and linked Malaysian extremists to a cell in Singapore that plotted to bomb Western embassies.

The government of Singapore said Saturday that more Al Qaeda members were likely still at large, even after the arrest of 30 suspected militants so far in the city-state and neighboring Malaysia.

Malaysian officials on Saturday said two men had been arrested in the past few days for alleged membership of an Islamic militant group called the Kumpulan Mujahiddin Malaysia.

The arrests brought to 15 the number of alleged members of the group detained since Dec. 9, Deputy Prime Minister Abdullah Ahmad Badawi said.

Prime Minister Mahathir Mohamad said some members of the Malaysian group admitted to being trained in Afghanistan by the Taliban and Usama bin Laden's Al Qaeda, blamed for the Sept. 11 terror attacks in the United States.

Mahathir said Saturday that the Malaysian militants have ties to Indonesia and the Philippines. "I believe Singapore is also (linked) ... but I do not have the facts," he was quoted as saying by the national news agency, Bernama.

It was the first time the Malaysian government has linked groups in Malaysia and Singapore, which is located on the southern tip of the Malay Peninsula.

Helped by evidence found in Afghanistan, Singapore authorities arrested 15 people in December on suspicion of Al Qaeda links. The suspects allegedly planned to blow up the U.S. Embassy and other diplomatic offices and targeted high-profile Americans in Singapore. Officials also say the militants stored four tons of the explosive chemical ammonium nitrate in Malaysia and were seeking more to make truck bombs.

Malaysia's Abdullah said investigators in the two counties would share information on the militant groups. All of the suspects were being held under laws in Singapore and Malaysia which allow indefinite detention without trial.

The nature of any links between the groups in Malaysia and Singapore is unclear. Officials say they may be part of a network of militant cells which are operating in several Southeast Asian countries and have plotted violence, and which may have direct connections with suspects in the attacks on the World Trade Center and Pentagon.

Singapore Prime Minister Goh Chok Tong warned on Saturday that authorities may have missed "quite a few members" of the militant group in his country.

"We cannot say that we have discovered everything," Goh said. "We must work on the assumption that there may be more cells."

Details of the Singapore plot shocked the city-state, one of Asia's wealthiest and most modern countries. The government says the cell was targeting "prominent members of the American community" and "surveyed" the U.S. Embassy, British High Commission, Israeli Embassy and Australian High Commission.

Singapore released a videotape, taken from an Al Qaeda leader's home in Afghanistan, showing one of the suspects apparently talking about possible targets.

In Malaysia, police are investigating whether some of the Malaysians arrested had contact with two hijackers involved in the Sept. 11 attacks and with Zacarias Moussaoui, who is charged with conspiring in the attacks.

The two hijackers and Moussaoui separately visited Malaysia in 2000. Police are investigating whether one of the Malaysian suspects let the hijackers stay at an apartment he owned near Kuala Lumpur.

Mahathir said this week about 50 Malaysians were involved with Al Qaeda and that Malaysian authorities had tracked down "quite a number" of them.

In a series of arrests starting in August, Malaysian authorities detained about two dozen people it accused of being members of the Kumpulan Mujahiddin Malaysia. It claimed the group was involved in bombings in Indonesia, a murder in Malaysia and of having links with Islamic separatists in the Muslim-dominated southern Philippines.