COLOMBO • One month after the Sri Lanka suicide attacks that killed more than 250 people, investigators say the bombers used "Mother of Satan" explosives favoured by the Islamic State in Iraq and Syria (ISIS), in a new indication of foreign involvement in the strikes.
Detectives yesterday told Agence France-Presse (AFP) that the backpack bombs used in the April 21 attacks on three churches and three hotels were made by local militants with ISIS expertise.
They named the explosive as triacetone triperoxide, or TATP, an unstable but easily made mixture favoured by ISIS militants who call it "Mother of Satan".
The explosive was also used in the 2015 attacks in Paris, by a suicide bomber who hit the Manchester Arena in England in 2017, and in attacks on churches in Indonesia one year ago.
ISIS has claimed that the Sri Lankan bombers operated as part of its franchise. But Sri Lankan and international investigators are anxious to know just how much outside help went into the attacks that left 258 dead and 500 injured.
"The group had easy access to chemicals and fertiliser to get the raw materials to make TATP," an official involved in the investigation told AFP.
Sri Lanka officials have said the National Thowheeth Jama'ath (NTJ), a local militant group blamed for the attacks, must have had foreign help to assemble the bombs. "They would have had a face-to-face meeting to transfer this technology. This is not something you can do by watching a YouTube video," said the official.
Detectives said the backpack bombs used in the April 21 attacks on three churches and three hotels were made by local militants with ISIS expertise. They named the explosive as triacetone triperoxide, or TATP, an unstable but easily made mixture favoured by ISIS militants who call it "Mother of Satan".
Investigators had initially believed that C4 explosives - a favoured weapon of Tamil Tiger rebels - were used, but forensic tests found TATP, which causes more burning than C4.
Police have also confirmed that 100kg of explosives found in January in the island's north-west was TATP.
They are checking the travel records of the suicide bombers as well as foreign suspects to see when and where bomb-making lessons could have been staged.
"It looks like they used a cocktail of TATP and gelignite and some chemicals in the Easter attacks. They were short of the 100kg of raw TATP that were seized in January," said the investigator.
Sri Lankan security forces have staged a series of raids since last month's bombings.
Police spokesman Ruwan Gunasekera on Sunday said 89 suspects are in custody.
And army chief Mahesh Senanayake last week said at least two suspects have been arrested in Qatar and Saudi Arabia, underscoring the international link.
On April 26, six militants, three widows of the suicide bombers and six of their children were killed at an NTJ safe house near the eastern coastal town of Kalmunai. Police found large quantities of chemicals and fertiliser there that was probably meant to make bombs, the authorities said.
The government has admitted that warnings from India of the looming attacks in early April were ignored.
The Sri Lankan who led the attacks on April 21, Zahran Hashim, was known to have travelled to India in the months before he became one of the suicide bombers. He was one of two bombers who killed dozens of people at Colombo's Shangri-La Hotel.
Hashim, one of seven bombers who staged the attacks, also appeared in an ISIS video that claimed responsibility for the attacks.
Another bomber, who was meant to have hit a fourth hotel, has been named as Abdul Latheef Jameel. He studied aviation engineering in Britain and Australia.
The authorities in the two countries are investigating whether he was radicalised while abroad.
Jameel blew himself up when confronted at a hideout after the attacks.