A second audio recording, presented as the voice of Turkish Prime Minister Tayyip Erdogan asking his son not to accept an amount of money on offer in a business deal but to hold out for more, was published on YouTube by an anonymous poster using a pseudonym on Wednesday.
Erdogan said a similar post on the video-sharing site on Monday, allegedly of him telling his son Bilal to dispose of large sums of cash as a graft investigation erupted, was faked by his political enemies.
"Don't take it. Whatever he has promised us, he should bring this. If he is not going to bring that, there is no need," the voice on the latest recording, presented by a user under the pseudonym Haramzadeler as that of Erdogan, says.
"The others are bringing. Why can't he bring? What do they think this business is? ... But don't worry they will fall into our lap," the voice says.
Reuters could not verify the authenticity of either recording.
"We are going to check whether the tapes are fake or not and no statement is planned at the moment," a senior government official told Reuters.
The recordings, which appeared within days of the ruling AK Party's official launch of a campaign for local elections at the end of March, are the latest and potentially most damaging allegations in a graft scandal that Erdogan has cast as concocted to unseat him.
Late on Monday, his office released a statement describing the first recordings as "completely untrue and the product of an immoral montage."
No company names are mentioned in Wednesday's audio recording but the voice purportedly of Bilal Erdogan refers to a "Mr. Sitki", saying he could not carry out a transaction.
An accompanying text within the YouTube clip says the reference is to Sitki Ayan, the chairman of Istanbul-based company Turang Transit Tasimacilik. The basis for that conclusion was not clear.
It could not immediately be determined what ties, if any, Turang or its chairman have to the Erdogan family.
Telephone calls by Reuters to the offices of Turang seeking comment were not immediately answered on Wednesday night.
Turang received a licence in 2010 to build part of a pipeline planned to carry Iranian and Turkmen gas to Europe through Turkey, according to its website.
It was granted incentives including tax exemptions on investments of up to 11.5 billion lira ($5.2 billion) from the government in December, according to the Economy Ministry's website.