Colombo Sri Lanka's police chief resigned from his post on Friday, two days after President Maithripala Sirisena asked him to step down over the security establishment's failure to avert the deadly Easter bombings.

Sirisena, who is also the defence minister, said Inspector General of Police Pujith Jayasundara resigned over failures which led to the attacks on three hotels and three churches on Sunday that claimed 253 lives.

"The IGP has resigned. He has sent his resignation to the acting defense secretary. I'll nominate a new IGP soon," the president said.

The police chief's resignation came a day after the country's defence secretary Hemasiri Fernando handed over his resignation letter to the president.

Sirisena had asked Fernando and Jayasundara to quit after their failure to prevent the blasts despite having prior intelligence.

Sirisena said the intelligence supplied by a friendly nation was not shared with him by officials. All they have done was to exchange letters among themselves," he said.

I asked both police chief and defence secretary why the information was not shared with me, they remained silent," he said.

He said the security lapse was also due to the current government's weakening of intelligence operations.

This is a reference to the arrest and trials against a handful of military intelligence officers who were responsible for attacks and murder of journalists, abductions and ransom taking, he said.

He said the power struggle in his government was because he had objected to the government's weakening of the security forces.

Sirisena said he would soon set up a Joint Operations Command to combat terrorism and each and every house would be checked for the safety of all citizens.

Top officials have acknowledged that Sri Lanka received intelligence about possible terror strikes ahead of the attacks, but both Sirisena and Prime Minister Ranil Wickremesinghe said that they did not receive the information.

Nine suicide bombers carried out a series of devastating blasts that tore through three churches and three luxury hotels on Easter Sunday.

The Islamic State group has claimed responsibility for the attacks, but the government has blamed a local Islamist extremist group National Tawheed Jamath (NTJ) for the attacks.

The president also confirmed that Sri Lankan Islamist extremist Zahran Hashim, the leader of the NTJ, died in the blast at the Shangri-La hotel.

Hashim led the attack on the hotel and was accompanied by a second bomber, Ilham Ahmed Ibrahim.

The president also appealed to the island nation not to view its minority Muslim community as terrorists in the wake of the attacks.

Sirisena said despite the attacks, the island's nine per cent Muslim minority must not be regarded terrorists.

We looked into banning the NTJ but we do not have laws to do that right now. We have to draft new laws. We will get this done soon," he said.

Information is that around 130-140 ISIS suspects are in the country. Around 70 are arrested, we will arrest them all very soon ending this (terror)," Sirisena said.

Police said that over 70 suspects, including five women, have been arrested as the Lankan authorities have intensified their search operations with the help of the army.

Today's Friday prayers were cancelled as a Muslim Theologists Group, Jammiyyathul Ulama asked Muslims to pray indoors. This was following information received that extremists could carry out more attacks.

The city and the immediate suburbs of Colombo looked deserted this morning. Most offices have allowed employees to work from home.

During the last 24 hours there have been no incidents reported," Brigadier Sumith Atapattu, the military spokesman, said.

He said the Sri Lankan Army would continue search operations for suspects linked to the terror group.