Three sources with direct knowledge of the case tells news agency Reuters that Sri Lanka was warned a few hours before the attacks took place.
321 people were killed in the attacks, which took place on easter Sunday in the three churches and four hotels. Islamic State on Tuesday claimed responsibility for the attacks.
A source in the indian government and a different source in the Sri Lankan defence tells Reuters that the indian intelligence service contacted Sri Lankan intelligence services two hours before the first attack to warn about a threat, which they said had targeted churches.
another source in Sri Lanka tells that the warning came hours before the first attack took place, and that the same warning was posted already on Saturday night, while the source in the indian government says that similar warnings were sent to Sri Lanka both 4. april 20. april.
Neither the Sri Lankan president or the indian foreign ministry has yet commented on the information.