Sri Lanka is holding a day of national mourning for the victims of Easter Sunday's bomb blasts as mass funerals for some of the 310 victims took place today.

A three minute silence was held at 08:30 local time in honour of the victims as a state of emergency remains in place following the attacks on three churches and four luxury hotels. 

Flags were lowered as people across the nation observed the silence, which was timed to coincide with the moment the first bomb exploded on Sunday. 

A mass funeral was held at St Sebastian's church in Negombo, one of the churches targeted in the attacks. 

The attacks were carried out by suicide bombers and have been blamed on a local Islamist group, National Thowheed Jamath (NTJ), although the group has not claimed responsibility. 

The NTJ came under scrutiny last year over the vandalism of Buddhist statues and in 2016, when one of its leaders was accused of inciting racism. It has no previous record of carrying out large scale attacks. 

Government spokesman Rajitha Senaratne said he believed the perpetrators had outside help. 

"We do not believe these attacks were carried out by a group of people who were confined to this country," he said.

"There was an international network without which these attacks could not have succeeded."

The Archbishop of Colombo, Cardinal Malcolm Ranjith, said at least 110 people were killed at St Sebastian's church. 

Scores more died when other bombs exploded at St Anthony's Shrine in Colombo and the Protestant Zion Church in Batticaloa, around 300km east of Colombo, as well as upmarket hotels, including the Cinammon Grand, Kingsbury, and the Shangri-La.

Zion Church announced on its Facebook page that it would also be holding funerals throughout Tuesday for dozens of people from its congregation killed in the attack.  The church lost at least 26 people and over a hundred more were injured.  Around half of the victims were reportedly children. 

Pastor Ganeshamoorthy Thirukumaran's teenage son was buried on Monday. 

"May the Dear Lord continue to comfort us all in this difficult time," the church said. 

Pastor Thirukumaran told Al Jazeera that he now believes he invited the suspected bomber into the church for service. 

He did not recognise the man but he says, "I asked him to sit down and stepped outside the building. Moments later, the bomb exploded." 

Police spokesman Ruwan Gunasekera said 40 people had been arrested in connection with the attacks. 

Scrutiny has also fallen to Sri Lanka's leaders, though, after it emerged that government officials had been warned of a possible attack. 

Telecommunications minister Harin Fernando posted images of a letter to Twitter entitled "information on an alleged plan attack" and naming the NTJ as a threat. 

"Serious action need to be taken as to why this warning was ignored [sic]," he said. 

Prime Minister Ranil Wickremesinghe has insisted he was not informed of the threat and has launched an inquiry into the attacks. 

He said: "We must look into why adequate precautions were not taken."