The Tamil National Alliance (TNA) MP, S Sritharan told parliament that the former defence secretary, Gotabaya Rajapaksa was the real "master" behind the Easter Sunday bombings.
His comments come amid widespread reports of close association between Gotabhaya and the now banned Islamist extremist organisation, National Thawheed Jammath (NTJ), which was one of the groups responsible for the attacks.
Pointing to the intense security situation in the North-East with checkpoints and military personnel on the streets, Sritharan said the army was happy about it.
"While getting checked like this in so many places, the army is delighted to do it. They are happy to do it. They are happy about the Tamil race being troubled by them," Sritharan told parliament last week.
Questionning who was really behind the bombings, Sritharan said, "if the army is trying to oppress a race with this much of happiness, then it is obvious that the army, its intelligence, and former President’s team are behind these matters."
"Gotabhaya Rajapakse is a master in this matter. He is a master of assassinations and white van kidnappings - because of this only, am I saying this without any doubt."
"Find out the truth behind [the bombings] first. Inquire the former president, former Secretary of defence and their team. Find out the truth. Make sure that the justice prevails."
St Anthony's Church, Colombo
Over 250 people were killed when Islamist extremist suicide bombers supportive of Islamic State detonated devices at luxury hotels and churches on Easter Sunday.
There has been increasing criticism over the government's failure to take action to prevent the attacks after it emerged India had warned Sri Lankan authorities repeatedly in the preceding weeks that such an incident was planned.
Questions have also been raised over the organisations' links with government security forces and intelligence, with reports that the intelligence authorities funded NTJ.
Last week a Sri Lankan parliamentarian said the former defence secretary Gotabaya Rajapaksa gave NTJ land for an office in Colombo.
Kurunegala District UNP MP Thushara Indunil however claimed that the NTJ received support from Rajapaksa, who announced that he would the running for president in elections set to be held later this year.
Indunil said the All Ceylon Jamiyathul Ulema had warned the Sri Lankan government “as early as 2014” about the emergence of the NTJ and Islamic extremists on the island. “If the former Defence Secretary was privy to this information, we ask of what he did then, knowing the threats it posed,” he said.
“He tried to divide the peaceful community of Muslims into two. He knew that it would help him in his political endeavours which is why he strengthened one group against the other. Basil Rajapaksa said that there are 200 such mosques and the defence secretary assisted in setting them up.”
One Sri Lankan soldier is currently on the run after authorities said they believed he had taught the attackers how to use explosives.
Cabinet spokesperson Rajitha Senaratne said that at least four army officers were involved in organising the assassination of police officers in Batticaloa last year, and claimed dozens of NTJ were on the payroll of Sri Lankan intelligence linked to Rajapaksa.