* Sale is part of 8-10 bln euro privatisation drive
* Govt plans to honour end-2014 sale deadline - source
* Post office to present industrial plan in coming weeks (Adds government source, detail, background)
ROME, June 10 (Reuters) - A public sale of shares in Poste Italiane by the end of the year is a "challenge" but one the Italian post office operator does not intend to back out of, its chief executive said on Tuesday.
The listing was announced last year as part of a wider privatisation drive aimed at cutting Italy's 2 trillion euro ($2.7 trillion) public debt, second only to Greece in the euro zone as a proportion of gross domestic product.
The government said it wanted to complete the 40 percent sale, which is expected to earn 4-5 billion euros, by the end of 2014, but there has been doubt about meeting the time limit.
"Given the complexity of the group and the time required in other privatisations, the deadline remains a great challenge but one we do not intend to avoid," Francesco Caio, who took over as chief executive in May, said in a statement.
Caio said state-owned Poste Italiane, whose wide-ranging business beyond mail delivery includes Italy's sixth-biggest bank, would present an industrial plan in the coming weeks.
A government source said it planned to honour the deadline.
"If there is a delay it will be a few months, not later than November. We mean to close the deal in 2014," the source said.
One of the banks running the offering said last week Poste Italiane, one of Italy's biggest employers with 146,000 workers, planned to list in Milan in the next 12 months.
Stakes in state-owned shipbuilder Fincantieri and air traffic control operator ENAV are also earmarked for sale in a drive to raise 8-10 billion euros over the next two years.
Without the planned disposals, Italy, which has long promised to divest some of its extensive corporate holdings, runs the risk of not complying with the European Union's fiscal compact on budget stability this year and next.
By floating on the market, Poste Italiane would follow Belgium's bpost and Britain's Royal Mail, which were both privatised in the last 12 months.
($1 = 0.7345 Euros) (Reporting by Valentina Consiglio, writing by Isla Binnie)