Such a sale would mean Rupert Murdoch's News Corp, which owns more than 40 per cent of Sky, would gain a powerful stake in New Zealand media.
Other potential buyers are said to be waiting for a firesale when the banks step in. These include Australian media companies Channel 9 and Seven Network.
A source said Ironbridge wanted to sell before strict new debt-repayment requirements come into force in November.
MediaWorks has shown it can still find money to invest in talent. This year it hired the provocative Paul Henry to host a show on RadioLive and front the broadcast group's election coverage - raking in a salary believed to be about $500,000.
Ironbridge partner Mike Hill, who led the purchase of Mediaworks in 2007, denied the business was cash-strapped and argued that television revenues at TV3 were up this year.
"We acknowledge that the economy has been tough over there but it is a great business, we are very happy with it," he said from Melbourne.
"We have enough funds to keep running the business."
Hill played down the sudden departure of Jason Paris, the TV boss head-hunted from TVNZ who lasted at TV3's Eden Tce headquarters for less than a year. Paris gave notice and will work his remaining six months from home.
Hill said there was no pressure to put MediaWorks on the sale block but indicated it would be willing to sell if the right offer came along. MediaWorks sources said Ironbridge would accept an offer of about half what was paid for it, about $360 million.
"Really, the only option is to sell," said one source. "It can't go on for years more unable to service debt.
"Sky is talked about as a buyer. It has come close to its peak market penetration and it could be attractive to grow the business by diversifying into radio."
Sky issued a five-word statement: "We don't comment on speculation."
TV3 has delayed starting production of its big-budget production of The X Factor, which is expected to cost about $300,000 per episode to make.
And newsreader Alistair Wilkinson last week jumped ship to become news director at Sky, which screens a daily TV news bulletin at 5.30pm on Prime, its free-to-air channel.
But Sky is thought to want a more competitive news service. TV3 ratings have improved for the key 6pm news bulletin. 3 News is running neck-and-neck with One News in the target age group of 25-54 years.
Earlier this year it was revealed that the Government "lent" $43 million to MediaWorks for radio licensing fees.
MediaWorks' radio operations are highly profitable but television has been stung by falling ratings figures and advertising revenues.
One option could be to sell the TV and radio operations or to invite the banks who have lent hundreds of millions of dollars to step in.
The source added: "The banks which funded that recapitalisation [last year] are watching them like a hawk.
"I suspect that something will be coming to a head this side of Christmas."
