The Belgian government has been looking into floating 30 percent of Belfius, which was created after the state bought the Belgian banking arm of Franco-Belgian lender Dexia in 2011 for 4 billion euros (3.53 billion pounds).

The finance ministry said in July, when announcing its plans, that the timing of the initial public offering (IPO) had not been taken.

Analysts had expected the sale to raise some 2 billion euros, helping to cut Belgium's national debt, although market turbulence has since cut the estimated value of the bank.

Dexia was almost entirely nationalised in the aftermath of the financial crisis and Belgium is still guaranteeing part of its borrowings.

(Reporting by Philip Blenkinsop)