Sri Lanka's newly elected President Maithripala Sirisena
Sri Lanka's newly elected President Maithripala Sirisena (C) arrives for his swearing-in ceremony in Colombo Reuters

The newly-elected Sri Lankan government has said it will be investigating the allegations of coup attempts made by outgoing president Mahinda Rajapaksa shortly after the results were announced.

The incumbent leader faced a surprise drubbing in the island nation's polling following which he said to have sought help from the army to stage a coup against the winner Maithripala Sirisena.

"People think it was a peaceful transition. It was anything but," Mangala Samaraweera, who is likely to be made Sri Lanka's foreign minister told reporters.

"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 [N K Illangakoon] refused to go along with him."

Rajapaksa conceded defeat as the results surfacing indicated that his former minister was securing an unassailable lead.

Shortly after praises were heaped on Rajapaksa for admitting the defeat and paving way for the smooth transition, one of the president-elect's spokespeople Rajitha Senaratne told a press conference in the capital Colombo: "The army chief was under pressure to deploy but he did not. He declined to do anything illegal."

"Even in the last hour, he [Rajapakse] tried to remain in office. Only when he realised that he had no other option, he decided to go."

The military has not made any comment on the allegations so far.

The new government have officials have assured there will be no vendetta against the outgoing members but insisted their wrongdoings will not go unpunished.

"We don't believe in revenge, but that does not mean we will not prosecute those accused of wrongdoing," Senaratne said.

Barring minor incidents, the elections remained largely peaceful.