More than 500 people were wounded in the blasts, police spokesman Ruwan Gunasekera said. The death toll overnight stood at 215. Eight coordinated explosions targeted Easter worshippers and high end hotels popular with international guests.
The blasts targeted St Anthony's Church in Colombo, St Sebastian's Church in the western coastal town of Negombo and another church in the eastern town of Batticaloa around 8.45 a.m. (local time) as the Easter Sunday mass were in progress.
Three explosions were reported from the five-star hotels - the Shangri-La, the Cinnamon Grand and the Kingsbury. Foreigners and locals who were injured in hotel blasts were admitted to the Colombo General Hospital.
The number of deaths have gone up to 290 with over 500 injured, Gunasekera said, adding that six Indians have been reported among the foreigners who had died.
Four of them died in the Colombo National Hospital while the bodies of two of them who succumbed to their injuries from the blast at the Shangri-La Hotel has been sent for further investigation, the National Hospital spokesperson said.
There was no immediate claim of responsibility, but police on Monday 24 people from the minority Muslim community were arrested and declined to give further details.
The government has said it will not disclose the details of the suspects involved in the attacks to prevent them from getting publicity. "Don't give extremists a voice. Don't help to make them martyrs," State Minister of defense Ruwan Wijewardene told reporters when asked for details of those in custody.
The blasts - one of the deadliest attacks in the country's history - shattered a decade of peace in the island nation since the end of the brutal civil war with the LTTE.