The top 40 richest people in Indonesia are worth US$88.6 billion collectively, up over four per cent from last year, according to the latest Indonesia Rich List published by Forbes.

Forbes attributed Indonesia's emerging middle class as helping to boost the wealth of some of the country's richest citizens, while cooling coal demand weakened the fortunes of several other tycoons.

Brothers R. Budi and Michael Hartono retained the top spot on the list with a fortune of US$15 billion.

The brothers saw their net worth increase US$1 billion partly due to the inclusion of their controlling stake in telecom outfit Sarana Menara Nusantara.

Their decade-old investment in Bank Central Asia, the mainstay of their wealth, is worth nearly US$11 billion.

They also own clove cigarette maker, Djarum, and have taken stakes in palm tree plantations and Indonesia's largest shopping mall, Grand Indonesia.

Eka Tjipta Widjaja was ranked number two with a fortune of US$7.7 billion, down US$300 million from last year.

His family's Golden Agri-Resources is the world's second-largest oil palm plantation company.

Susilo Wonowidjojo was ranked third on the list and the year's biggest dollar loser. He saw his fortune drop by US$3.1 billion to US$7.4 billion, as shares of his family's clove cigarette maker, PT Gudang Garam, tumbled nearly one-fourth, due to a 22 per cent drop in profits in the first nine months of 2012.

While clove cigarettes remain popular in Indonesia, the Unoted States has banned them due to concerns that the flavourings appeal especially to children.

Anthoni Salim and Chairul Tanjung ranked no. 4 and no. 5 on the list respectively.

Anthoni Salim's company has diverse interests in cement, retail and telecommunications, and his fortune jumped by US$1.6 billion to US$5.2 billion.

Chairul Tanjung saw his fortune increase by US$1.3 billion to $3.4 billion, thanks to the strength of his Trans Corp Media. His CT Corp. has interests in Bank Mega, theme parks and operates Armani and Jimmy Choo franchises.

In a statement, Justin Doebele, Chief Editorial Advisor of Forbes Indonesia, said: "The stable economic growth of Indonesia this year has boosted the wealth of many members of our rich list, especially those involved in providing goods and services to emerging middle class consumers."

Newcomer to the list, Lim Hariyanto Wijaya Sarwono (no. 30), one of the country's latest billionaires, made his debut with a net worth of US$1.03 billion after listing his palm oil outfit, Bumitama Agri, on the Singapore Exchange.

Other newcomers include Alexander Tedja (no. 36) with a net worth of US$790 million, Sudhamek (no. 38) at US$760 million and Eddy Kusnadi Sariaatmadja (no. 40) at US$730 million.

Several of the tycoons who have business in the coal sector suffered a decline. They include Low Tuck Kwong (no. 12) who was this year's biggest percentage loser.

He saw his wealth slip 46 per cent to US$2 billion. Another tycoon with substantial coal interest, Aburizal Bakrie, fell off the list this year.

The coal industry, one of Indonesia's most important sectors, was under pressure due to falling prices and weakened demand from China.

The minimum to make the list rose to US$730 million, US$100 million more than a year ago.