Sri Lanka has postponed a tour of Pakistan Under-19 team following the Easter Sunday suicide bombings that killed 253 in the island country, a Sri Lankan cricket board (SLC) source told Reuters on Saturday.

The militant Islamic State group has claimed responsibility for the suicide bomb attacks on three churches and four hotels all but one of which were in the capital, Colombo.

The Pakistan Under-19 side, captained by Rohail Nazir, was scheduled to arrive in Sri Lanka on April 30 to play two four-day matches, followed by three one-dayers. Galle and Hambantota were the venues for the matches.

"The request was to postpone it for a short time," the source said referring to last Sunday's attack.

"Discussions are ongoing with the Pakistan Cricket Board (PCB) (and) Sri Lanka Cricket is trying to bring Pakistan to play the tournament at a later date.

"It will depend on the PCB and the SLC will also look at the security situation before taking a final decision."

Additionally, sources with the PCB confirmed that the board had been informed of SLC's decision.

There were more deaths in Sri Lanka after a shootout between troops and suspected Islamist militants erupted on Friday evening in Sainthamaruthu in Ampara district, to the south of the town of Batticaloa, site of one of the Easter Sunday blasts.

Authorities have warned there could be more attacks targeting religious centres following the bombings, which shattered the relative calm that Buddhist-majority Sri Lanka had enjoyed since a civil war against mostly-Hindu ethnic Tamil separatists ended a decade ago.

The US State Department, warning that terrorist groups were continuing to plot attacks, urged citizens to reconsider travel to Sri Lanka.

Pakistan Under-19 are scheduled to tour South Africa for seven 50-over matches from June 19-July 7 as part of their preparations for next year's World Cup in the same country.

Additional reporting by Abu Bakr Bilal