Alaina Teplitz, the US ambassador to Sri Lanka, said that some militants involved in the Easter Sunday attacks may be at large and could be plotting fresh attacks.
“Tremendous progress has been made towards apprehending those plotters but I don’t think the story is over yet,” Teplitz said in an interview with Reuters.
“We do believe that there is active planning under way.”
Sri Lankan security forces are continuing a high level of alert amid intelligence reports that the militants were likely to strike before the start of the holy Islamic month of Ramadan which is scheduled to begin on May 6.
Numerous arrests have been made since the string of devastating attacks on April 21 which killed 253 people, including 42 foreign nationals.
On Sunday India's Ministry of External Affairs warned its citizens against all non-essential travel to Sri Lanka.
"In view of the prevailing security situation in Sri Lanka in the aftermath of terror attacks on April 21, 2019, Indian nationals intending to travel to Sri Lanka are advised not to undertake non-essential travel," the advisory said.
A number of the reports following the bombings state the Sri Lankan authorities were warned by their Indian counterparts about the attacks at least on three occasions in the preceding weeks.