COLOMBO, May 11 (Reuters) Sri Lankan President Gotabaya Rajapaksa said on Wednesday (May 11) he would appoint a new prime minister and cabinet this week, after his elder brother and former premier Mahinda Rajapaksa resigned following deadly violence in the country.

The new prime minister and cabinet will command a majority in the 225-seat parliament, Rajapaksa said, adding he will bring constitutional reforms to grant more power to the parliament.

"I am taking steps to form a new government to control the current situation, to prevent the country from falling into anarchy as well as to maintain the affairs of the government that have been halted.

The president's statement followed comments from Sri Lanka's central bank governor earlier in the day, who said he would quit within weeks unless political stability was restored.

P Nandalal Weerasinghe, appointed central bank chief last month to help the island nation of 22 million people find a way out of its worst economic crisis in history, said a stable government was essential to stop the turmoil.

"I have clearly told the president and other political party leaders that unless political stability is established in the next two weeks I will step down," Weerasinghe told reporters.

"Without political stability, it doesn’t matter who runs the central bank," he said, "There will be no way to stop the economic deterioration."

Ordinary Sri Lankans blame the government led by President Gotabaya Rajapaksa and his family for a meltdown in the Indian Ocean nation that reduced reserves to just about US$50 million, stalling most imports and bringing massive shortages of essentials including cooking gas, fuel and medicine.

After more than a month of mostly peaceful demonstrations, public anger exploded into violence this week, when ruling party supporters stormed an anti-government protests camp, triggering clashes nationwide and pushing the prime minister to step down.

Mahinda Rajapaksa, the president's older brother, said he was resigning with the hope of a new, unity government taking over.

But with mobs targeting ruling party politicians, the former prime minister, once hugely popular, was whisked away to a military base in the country's northeast, the defence secretary said.

"He will remain there for the next couple of days and when the situation is normalised, he can be moved to a location of his choice," Kamal Gunaratne said.

On Wednesday, police and soldiers patrolled the streets of Weeraketiya, the Rajapaksa family's home town, where shops and businesses were shut by a curfew that will run until Thursday morning.