The SLFP has decided to quit the national unity government, the party spokesperson, MP Thilanga Sumathipala told reporters on Sunday night.
The announcement came following a meeting between senior UPFA members, including senior figures within the SLFP, and the president, Maithripala Sirisena.
Mr Sirisena has urged them to wait for a decision from the Supreme Court regarding the president's power over the appointment of the prime minister, before making such a decision, the spokesperson added this morning.
"President Maithripala Sirisena has requested the UPFA members in the government not to quit the National Government, until the Supreme Court conveys its opinion, as it could destabilize the country," Mr Sumathipala said.
Sri Lanka's unity government was thrown into crisis this month after the country's local government elections delivered a bruising defeat to both main parties of the coalitions, and a victory to the newly established party of the former president, the SLPP.