Sri Lanka's new government on Sunday accused toppled strongman Mahinda Rajapaksa of having tried to stage a coup to cling to power after losing last week's presidential election.
Rajapaksa, South Asia's longest-serving leader before losing last Thursday's polls, had been widely praised for conceding defeat to Maithripala Sirisena before the final results had been announced.
But a top aide to Sirisena told reporters that Rajapaksa had in fact tried to persuade the army and police chiefs to help him stay in office with the use of force.
"People think it was a peaceful transition. It was anything but," Mangala Samaraweera, who is expected to be named as Sirisena's foreign minister, told a press conference.
"The first thing the new cabinet will investigate is the coup and conspiracy by president Rajapaksa.
"He stepped down only when the army chief and the police inspector general (NK Illangakoon) refused to go along with him."
Illangakoon was "very vocal and did not want to be a party to this coup", while army chief Daya Ratnayake also refused to deploy troops for Rajapaksa to seize power, said Samaraweera.
The attorney general's department had also warned that there would be "dangerous consequences", he said.
Samaraweera said diplomatic pressure had in addition been brought to bear on Rajapaksa, who came in for international criticism during his near-decade in office over his administration's human rights record.
Critics also accused him of increasing authoritarianism and a culture of nepotism and corruption.
"Some world leaders also spoke with president Rajapaksa and prevailed on him to ensure a peaceful transition," Samaraweera said.
"I don't know who had spoken (to him), but we know some leaders did talk to him."
US secretary of state John Kerry and even Sirisena himself had thanked Rajapaksa for quitting in the early hours of Friday, after his defeat in an election he had seemed certain to win when he called it in November.
The head of the army was not immediately available for comment. But military spokesman Ruwan Wanigasooriya said he was "not aware of such a coup attempt".
Samaraweera said it was important for the new administration to disclose what had happened while results were being released, and an independent investigation probe would be a priority.
Join hands for reform
In an address to the nation, Sirisena appealed for a government of national unity to carry out the political and economic reforms he promised in his election campaign.
The new president wants to establish independent commissions to run the police, the public service and the judiciary and to transfer many of his executive powers to parliament.
"I hope all the parties will accept my invitation and join hands to ensure good governance, rule of law and carry out the reforms we have promised to improve the quality of life for our people," he said from the hill city of Kandy.
The president invited all parties to join his cabinet, which is expected to be finalised by January 19 when parliament will open.
He reiterated a call to normalise relations with western nations and neighbouring India.
Rajapaksa had alienated many foreign leaders by refusing to allow an international probe into allegations of mass civilian casualties in the brutal finale to Sri Lanka's 37-year Tamil separatist war in 2009.
Another top lieutenant said Sirisena had already received the backing of more than 40 lawmakers previously loyal to Rajapaksa, virtually assuring approval for his programme of radical constitutional reforms.
"We now have more than we need in parliament," Rajitha Senaratne told AFP.
Sirisena previously had the backing of 89 lawmakers and needed another 24 for a simple majority in the 225-member house.
The new leader, who is himself a defector from Rajapaksa's party, has already pledged to reverse many of the constitutional changes made by his predecessor which gave huge powers to the president.
Even Rajapaksa's Sri Lankan Freedom Party has said it would support Sirisena's constitutional reforms, making their enactment a formality.
Sirisena quit Rajapaksa's cabinet in November to emerge as an opposition unity candidate in the January 8 polls, triggering a mass defection of lawmakers.
While Rajapaksa retains significant support from the majority Sinhalese community, anger had been growing over rising levels of corruption.
Rajapaksa had installed relatives in some of the most sensitive posts, including his younger brother Gotabhaya as defence secretary.