Indonesia’s president has decided to move the capital of the world’s fourth most populous country away from the crowded main island of Java, but has yet to finalise a new location, the planning minister says.

President Joko Widodo’s decision comes less than a fortnight after private pollsters said he had won an April 17 presidential election, although official results are not due until May 22.

His challenger, Prabowo Subianto, has also claimed victory.

“The president chose to relocate the capital city to outside of Java, an important decision,” Minister Bambang Brodjonegoro told a news conference after a cabinet meeting on Monday.

Mr Brodjonegoro said the administration had yet to pick a new location, but was looking at the eastern side of the sprawling archipelago.

At the opening of his cabinet meeting, Mr Widodo stressed the need for new thinking about the future.

“We want to think in a visionary way for the progress of this country and moving the capital requires thorough and detailed preparation,” he said.

The current capital, Jakarta, is home to more than 10 million people. About three times that number live in the surrounding towns, adding to the area’s severe congestion.

The BBC reports that the idea of moving the capital has been floated several times since Indonesia gained independence from the Dutch in 1945.

In 2016, a survey found that Jakarta had the world’s worst traffic congestion. Government ministers have to be escorted by police convoys to get to meetings on time.

Mr Brodjonegoro said snarl-ups in Jakarta cost the economy 100 trillion rupiah ($A9.9 billion) a year.

The low-lying capital is also prone to flooding and is sinking due to over-extraction of ground water.

Mr Brodjonegoro said that, in making his decision, Mr Widodo had also taken into account that nearly 60 per cent of Indonesia’s 260 million people live in Java and economic activities are concentrated there,

During the recent election campaign, Mr Widodo promised to spread economic development more evenly outside Java.

The planning minister did not estimate the cost of moving the capital but said the president had ordered the finance ministry to come up with a financing scheme that allowed participation of private investors.

He said moving the capital could take up to 10 years, citing examples such as Brazil and Kazakhstan.

-with AAP