Belgium considers sale of BNP Paribas shares -paper

* Sale of stake expected by bankers for months

* Loss on sale would be "acceptable" for Belgium -investor

* Belgian govt, BNP (Paris: FR0000131104 - news) decline to comment

BRUSSELS/PARIS, Sept 18 (Reuters) - The Belgian government may sell part of its 10.3 percent stake in French bank BNP Paribas to bring the country's debt below 100 percent of annual economic output, two Belgian business newspapers reported on Wednesday.

A potential sale of Belgium's stake - worth around 6.3 billion-euros ($8.41 billion) - in France's biggest bank, has been mooted as likely by investment bankers for months. It would mark another milestone in state exits from holdings in European banks resulting from bailouts in the 2008 financial crisis.

Belgium took its stake in BNP Paribas (Milan: BNP.MI - news) following a bailout of Belgian financial group Fortis (Other OTC: FRTSF - news) , which was taken over by the French bank as part of a state-backed rescue.

A sale by Belgium would follow on from the UK government's sale of a 6 percent stake in Lloyds, which has raised expectations the UK might sell its entire stake by mid-2015.

Belgium faces a potential loss on the BNP Paribas stake, according to bankers and investors. The bank is still trading below the purchase price of 68 euros per share despite a rebound in European bank stocks, in which BNP Paribas's shares have risen almost threefold from 2011 lows.

"At current market levels the loss for the Belgian state would be acceptable ... It is plausible that they are really looking for a way to sell this stake," said Yohan Salleron, fund manager at Mandarine Gestion, which owns BNP shares.

"A logical outcome would be for BNP to buy back the shares ... That would be the best thing for the shareholders."

The Belgian prime minister's office declined to comment and BNP Paribas declined to comment.

BNP Paribas shares were flat at 50.39 euros at 0830 GMT.

A Paris-based trader said a sale of a 5-percent stake seemed "likely".

Belgium has agreed with the European Commission to keep its debt below 100 percent of gross domestic product, and would need to find a further 1.8-2.0 billion euros ($2.4-$2.7 billion) from privatisations to do that, budget minister Olivier Chastel said last week.

Selling around 3 percent of BNP Paribas would be sufficient to raise 2 billion euros to reduce the country's debt, business dailies De Tijd and L'Echo wrote.