* Shareholders want to inject new energy into exchange: source
* Warsaw bourse is in long-running talks on tie-up with Vienna
* Supply of new public offers drying up (Updates number of listings on bourse in paragraph 7)
By Adrian Krajewski
WARSAW, May 15 The controlling shareholders in the Warsaw stock exchange are considering appointing Poland's Deputy Treasury Minister Pawel Tamborski as chief executive of the bourse, several sources close to the shareholders said.
Tamborski, a former head of investment banking in UniCredit's Polish arm and at Wood & Company, declined to comment on the issue, as did the stock exchange.
The treasury ministry said in a statement emailed to Reuters that it had not yet recommended a candidate for the bourse chief executive's job and would not comment on media reports.
The state-controlled bourse is the biggest stock market in central Europe. The holder of the CEO's job, Adam Maciejewski, was appointed in January 2013 for a term which ends in the middle of this year.
Under Maciejewski, talks on a tie-up with the Vienna bourse have dragged on, while the Warsaw exchange faces challenges attracting new investors.
"The treasury wants a markets man on the job to breathe new life into the Warsaw bourse," one of the sources said, on condition of anonymity.
According to revised data released by the stock exchange, it has 455 listed companies - 48 of them foreign - with a combined market capitalisation of around 900 billion zlotys ($294.5 billion).
Poland's privatisation programme has generated a steady stream of public offerings on the bourse, attracting new investors. But there are now few state-owned assets left to sell off, leaving the bourse at a crossroads.
The tie-up with the Vienna stock exchange, which also owns smaller exchanges in Prague, Budapest and Ljubljana, could strengthen Warsaw's position against its rivals in Frankfurt and London.
But talks between Warsaw and Vienna have now been going on for over a year with no sign of an imminent conclusion.
In another challenge to the bourse, a reform of Poland's state-mandated pension system could reduce the appetite for equities among private pension funds.
Those funds have for a long time been major investors on the Warsaw exchange and eager participants in public offerings. ($1 = 3.0557 Polish Zlotys) (Reporting by Adrian Krajewski and Pawel Sobczak; Editing by Christian Lowe and Susan Thomas)