COLOMBO (REUTERS) - Three lawmakers from Sri Lankan President Maithripala Sirisena's party defected to the government of Prime Minister Ranil Wickremesinghe on Tuesday (Dec 18) after a dispute between the two leaders.

The island nation was plunged into crisis in October after Sirisena replaced Wickremesinghe with former president Mahinda Rajapaksa, without the backing of Parliament, leading to protests and downgrades of Sri Lanka's debt.

Rajapaksa, best known for crushing a long-running insurgency in the north of the country and drawing Sri Lanka closer to China, failed to win a parliamentary majority and resigned last Saturday as a government shutdown loomed.

Wickremesinghe was then sworn in as prime minister for the fifth time in a remarkable comeback.

"We joined the government... as the party and the country have been dragged into a difficult position," Vijith Wijayamuni Soysa, one of the three lawmakers told Parliament.

With the latest defections, Wickremesinghe has the backing of 120 legislators in the 225-member Parliament.

Last Thursday, Sri Lanka's Supreme Court ruled that Sirisena's decision to dissolve Parliament before the end of its term was unconstitutional, a judgment that eventually led to the return of Wickremesinghe as prime minister.

Members of his ruling United National Party and at least six opposition MPs want to oust Sirisena through an impeachment, though that needs a two-thirds majority in Parliament.