One of the suicide bombers involved in the Easter Sunday attack in Sri Lanka studied in Australia, the deputy defence minister said.
Ruwan Wijewardene said in a press conference it is believed there were nine suicide bombers in total.
“We believe one of the suicide bombers studied in the UK and later on did his postgraduate (degree) in Australia before coming back to settle in Sri Lanka,” Mr Wijewardene said.
“What we can say is some of the suspected bombers, most of them are well-educated and come from maybe middle or upper middle class so are financially independent and their families are quite stable.
“That’s a worrying factor in this because some of them have studied in various other countries.”
He confirmed 60 people have been arrested over the attacks, and all were Sri Lankans.
“They have been arrested on possible links to the attack,” Mr Wijewardene said.
The deputy defence minister said authorities were gathering information from as many sources as possible to help with further investigations.
The bombings in Sri Lanka on Easter Sunday have killed more than 350 people and injured about 500.
Mr Wijewardene suggested on Tuesday the bombings were retaliation for the attack on mosques in New Zealand in March.
"The initial investigation has revealed that this was in retaliation for the New Zealand mosque attack,” he told parliament.
Islamic State later claimed responsibility for the bombings but did not give evidence to back it up.
Australians killed in Sri Lanka attacks
Two Australians killed in the Sri Lankan bombings were identified as a mother and daughter who had been living in the country for several years.
Manik Suriaaratchi and her daughter Alexendria, 10, were two of the more than 350 killed in the bomb blasts that ripped through three churches, three luxury hotels and a guesthouse on Sunday about 8.45am.
An Australian father described the heartbreaking moment he found his wife and daughter.
Sudesh Kolonne had briefly left the church in Negombo after a service when a bomb went off.
"There was a bomb blast, I heard a huge noise and I jump into the church and I saw that my daughter and my wife was on the floor," he told ABC in Colombo.