SYDNEY (DPA, AFP) - One of the suspected ringleaders of the Easter Sunday suicide attacks which killed at least 253 people was investigated by Australian authorities for his links with a suspected key Islamic State in Iraq and Syria (ISIS) recruiter, local media reported on Friday (April 26).

Abdul Lathief Jameel Mohamed came to the attention of the authorities in 2014 when he was linked to several counter-terrorism targets, the Australian newspaper said citing intelligence sources.

According to the paper, Abdul Lathief was investigated by Australia's Joint Counter Terrorism Team in 2014, after he had left the country, and was connected to Australian-born Neil Prakash, a suspected key ISIS recruiter currently awaiting trial in Turkey.

Abdul Lathief had become withdrawn and deeply religious while studying for a postgraduate technology degree at Melbourne's Swinburne University from 2009 to 2013, the report said.

Ms Samsul Hidaya, his sister, told the Daily Mail he returned to Sri Lanka from Australia "a different man". He was withdrawn and humourless and berated relatives for not being religious enough.

"He had a long beard and had lost his sense of humour," she told the Mail.

Following his time in Australia, Abdul Lathief returned to Sri Lanka, where he completed courses in radical Islamic teachings.

He is then believed to have travelled to Syria where he joined ISIS before returning to Sri Lanka once more.

Sri Lankan authorities suspect Abdul Lathief of being one of the leaders of the nine suicide bombers, believed to be members of Islamist group National Thowheeth Jama'ath and ISIS, who carried out the Easter attacks.

Meanwhile, Australian counter-terrorism police said it would assist Sri Lankan authorities with their investigation and are probing Abdul Lathief's time living in Melbourne.

The Australian Federal Police refused to say whether the 36-year-old was known to them or whether he was radicalised while living in Australia.

"As there is an ongoing investigation into the attacks, it would not be appropriate to comment," a spokesperson said.