The UNF-led opposition has described it as being the result of a constitutional conspiracy.
In an address to the nation, Maithripala Sirisena said the main reason for replacing Ranil Wickremesinghe was the conspiracy to assassinate him and the former defence secretary.
However, a new theory has surfaced, after Weeratunga made a facebook posting to wish Dudley Sirisena, brother of the president and owner of Araliya Rice, on his birthday.
In that, Weeratunga also thanks him for proposing to the president that Rajapaksa be appointed the premier.
Given below is the fb posting by Weeratunga: