At the Sri Lanka Freedom Party's (SLFP) central committee meeting held last night, some members of the party had criticised the government's direction to remain with the coalition, party sources said.
It has been speculated for some months now that at least seven SLFP members holding positions in the unity government may leave to join the opposition or stay independent in parliament.
Sirisena took over the SLFP from former strongman Mahinda Rajapaksa after the latter was defeated in the 2015 presidential election.
After Sirisena's victory, Rajapaksa handed the party reigns to Sirisena. This caused a division within the SLFP with supporters of Rajapaksa forming a joint opposition
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Sirisena won the election with the support of the UNP and Sirisena loyalists are sharing government positions with the UNP.
Despite the action by Rajapaksa's loyalists to defy him, Sirisena has been applying restraint in taking action against them.
The party sources said that at last night's meeting, Sirisena had once again stressed on the need for party unity.