The United States on Saturday urged political parties in Sri Lanka to abide by the Constitution and refrain from violence, a day after the country’s President Maithripala Sirisena sacked his former ally Ranil Wickremesinghe as the prime minister.

On Friday, Sirisena replaced Wickremesinghe with former President Mahinda Rajapaksa. This came after Sirisena’s United People’s Freedom Alliance withdrew from the coalition government, throwing the country into a constitutional crisis.

The South and Central Asia Bureau of the US State Department tweeted that it was “following events” in Sri Lanka. “We expect the government of Sri Lanka to uphold its Geneva commitments to human rights, reform, accountability, justice, and reconciliation,” it said.

United Kingdom’s Minister of State for Asia and Pacific Mark Field said he was following the events in Sri Lanka “closely and with concern”. “We call for all parties and competent authorities to ensure that the constitution is respected and due political process followed,” he tweeted.

The UK government also updated its foreign travel advice on Sri Lanka, saying there were “reports of rapid political developments” in the country. It asked travellers to exercise vigilance and avoid demonstrations or large political gatherings.

On Saturday, Sirisena issued two gazette notices making Rajapaksa the new prime minister, PTI reported. Wickremesinghe said Rajapaksa’s swearing-in was “illegal and unconstitutional” and vowed to prove his majority in Parliament. “I will continue to be the prime minister,” he said. “Mahinda Rajapaksa’s appointment is unconstitutional.”

Last week, Sirisena accused Wickremesinghe’s United National Party of not taking seriously an alleged plot to assassinate him and former Defence Secretary Gotabaya Rajapaksa, the brother of Mahinda Rajapaksa.

Sirisena was chosen president in 2015 largely because of votes from Wickremesinghe’s party, ending Rajapaksa’s almost decade-long rule. However, both the ruling parties suffered heavy defeats in the local elections in February. Later, Sirisena aides supported a no-confidence motion against Wickremesinghe, who survived after a majority of legislators backed his government.