A Sri Lankan soldier stands guard near a car explosion after the police tried to defuse a bomb near St. Anthony's Shrine in Colombo on April 22, 2019, a day after the series of bomb blasts targeting churches and luxury hotels in Sri Lanka.

Jewel Samad | AFP | Getty Images

A Sri Lankan soldier stands guard near a car explosion after the police tried to defuse a bomb near St. Anthony’s Shrine in Colombo on April 22, 2019, a day after the series of bomb blasts targeting churches and luxury hotels in Sri Lanka.

Sri Lankans woke to emergency law on Tuesday as authorities searched for those behind suicide bomb attacks on churches and luxury hotels that killed 290 people at the weekend, with the focus turning to militants with links to foreign groups.

No group has yet to claim responsibility for Easter Sunday’s attacks on three churches and four luxury hotels that also wounded about 500 people.

Police spokesman Ruwan Gunasekera said the number of people arrested since Sunday had risen from 24 to 40. They are mainly Sri Lankans, although Gunasekera said police were investigating whether foreigners were involved in the attacks carried out by seven suicide bombers.

The president’s office declared that emergency law would come into effect from midnight, giving police extensive powers to detain and interrogate suspects without court orders. An overnight curfew was also put into effect.

The declaration came after nerves were frayed even further in the seaside capital Colombo when explosives went off on Monday near one of the churches hit in Sunday’s attacks while bomb squad officers were working to defuse a device.

CNN reported the blast was a controlled detonation.

Tuesday was also declared a national day of mourning.

The attacks brought a shattering end to a relative calm that had existed in the Indian Ocean island since a bitter civil war fought by Tamil separatists ended 10 years ago and raised fears of a return to sectarian violence.

It also underlined concerns over fractures in the Sri Lankan government, with questions raised over whether an intelligence tip-off was shared at the appropriate levels.

A government spokesman has said an international network was involved in the bombings but suspicion has focused on Islamist militants in the Buddhist-majority South Asian country. The nation of about 22 million people also has significant numbers of Hindus, Muslims and Christians.

The Washington Post quoted an unidentified law enforcement official as saying Federal Bureau of Investigation (FBI) agents were being sent to Sri Lanka to assist in the investigation.

The FBI has also offered laboratory expertise to test evidence and analysts were scouring databases for information that might shed light on tea attacks, the Post said.