Malaysian police have discovered four tonnes of ammonium nitrate, a key bomb-making ingredient which was used in the Bali bombings.
The same chemical was used in the Bali bombing
The fertiliser chemical was found buried in a palm oil plantation near Muar, in the southern Malaysian state of Johor.
Police told the BBC that they were still keeping an open mind about the find and that it was premature to draw conclusions.
There had been speculation that the cache was meant for use in a terrorist attack on Western targets in Singapore, which was foiled in December 2001.
The discovery follows a series of arrests in Southeast Asia of suspected members of the militant group Jemaah Islamiah, which is believed to have links with Osama Bin Laden's al-Qaeda network.
The breakthrough came two weeks after police detained Mohamad Amin Musa, a man who police say is suspected of arranging the training of new recruits for JI in the region.
Mr Amin, 29, worked on the plantation which belonged to his father.
He is also reported to be a cousin of Tufik Abdul Halim, a Malaysian who is serving a life sentence in Indonesia for a bombing campaign.
He was detained under Malaysia's Internal Security Act, which allows for indefinite detention without trial.
Malaysian police have arrested over 80 suspected Muslim militants under the Act, many of them allegedly members of Jemaah Islamiah, otherwise known as JI.
JI is a radical group whose aims are to create a Pan-Islamic state covering Malaysia, the southern Philippines and Indonesia.
They are believed to be behind the Bali bombing, which killed 202 people in October 2002.
Ammonium nitrate was the chemical used in the Bali bombings, and is particularly suited to truck bombs.
In December 2002, Indonesian police found half a ton of ammonium nitrate on Sulawesi island.