President Joko Widodo has quelled doubts about whether Indonesia is serious on moving its capital to Kalimantan, a huge enterprise that would require massive funds and the full backing of Parliament.

Parliament would have to pass a law as the legal basis to realise the President's plan for the move.

"On this historic opportunity, may God bless us, I would like to ask for approval and support from Parliament, from the seniors and prominent figures across Indonesia, that I hereby would like to move our capital to Kalimantan," Mr Joko declared in an annual speech ahead of Indonesia's Independence Day today.

Under the relocation plan, Jakarta will be the commercial capital of South-east Asia's largest economy, while a new city will become Indonesia's administrative capital - akin to the respective roles played by Kuala Lumpur and Putrajaya in Malaysia.

The government is expected to choose the new administrative capital from three regions on the island of Borneo - in East Kalimantan, Central Kalimantan and South Kalimantan.

Officials have said a major underlying reason for the plan to find a new capital is an environmental one, as Jakarta is overdeveloped and overcrowded.

The coastal metropolis of 10 million is sinking fast too, at 10cm a year on average, as its residents dig deep wells to tap raw water because of the city's poor supply networks. Another 30 million people live in Jakarta's neighbouring cities.

Observers have in the past doubted the ability of the country to go ahead with any plan for a new capital largely because of the huge expenditure involved amid unfavourable economic conditions and tight spending limits.

Earlier this month, National Development Planning (Bappenas) Minister Bambang Brodjonegoro said funding would come not only from the state coffers, but also from the private sector.

Mr Bambang said that financing could also be derived from renting out government-owned property in Jakarta, although many have dismissed the notion that this could lead to raising substantial funds.

Bappenas has been tasked by Mr Joko with conducting a feasibility study on the planned move.

Mr Bambang has a reputation for being over-optimistic in his projections. When he was replaced as finance minister in mid-2016, his successor Sri Mulyani Indrawati had to cut a 133 trillion rupiah (S$13 billion) spending plan to realistically correspond to the amount of tax collected.