Death toll in Sri Lanka's bomb attacks on Sunday rose to 300.
Police detained 24 people on suspicion of being linked to attacks targeting some churches and hotels, where about 500 other people wounded.
No name has undertaken the responsibility of the attacks so far.
Sri Lanka's Telecommunications Minister Harin Fernando took to Twitter with an image that he claims showed a memo warning of a possible attack headed information of an alleged plan attack.
"Some intelligence officers were aware of this incidence. Serious action needs to be taken as to why this warning was ignored," Fernando wrote.
The country's Prime Minister Ranil Wickremesinghe has acknowledged 10 days ago before the attacks that there was some prior information of a possible attack but he told reporters those concerns had not been passed onto ministers.
Curfew was declared to be valid on the entire island since the morning from 6 pm to 6 am local time in Sri Lanka.
Restrictions have also been imposed on social media networks and messaging applications in the country.
Authorities said some of the attacks were suicide bombings.
Among those killed in the attacks, there were 35 foreigners.
Turkiye's Sri Lankan Ambassador Tunca Özçuhadar announced that two Turkish engineers also died in the attacks.
On the other hand, Sri Lanka Police reported that a workplace of a Muslim was arson on Sunday night in Kalutara town and a mosque in the town of Puttalum was attacked by Molotov cocktails.
Police did not disclose information about any damage as a result of the attacks.
There are occasional conflicts between Muslims and Buddhists in the country where most of the population is Buddhists.
Curfew was declared in some parts of the country last year following attacks of Buddhists on mosques and works places owned by Muslims. (ILKHA)