Aleksandar Vucic, the Serbian defence minister, has accused the local police of phone-tapping him and President Tomislav Nikolic, along with other senior officials, blaming a group within the Interior Ministry.
The statement on Friday came after Vucic said he received information about the surveillance days earlier.
Vucic told the Reuters news agency: "A group under orders from [within] the Interior Ministry has been eavesdropping on top state officials including me and President Nikolic".
In an interview broadcast on local TV, Nikolic admitted that his phone had been tapped and said: "We have entered a snake pit, [consisting of] the people who are using positions in many [state] services ... who dared to eavesdrop on me and Aleksandar Vucic."
"There will be an investigation and soon we will see what this is all about," he added.
Vucic is also the first deputy prime minister and tasked with fighting organised crime, corruption and overseeing the work of intelligence agencies.
One of the stipulations posed by the European Union for Serbia's entry into the European bloc include rooting out high-level corruption, nepotism and organised crime.
The Socialist-nationalist government that came to power in July has pledged to eradicate these issues and Vukvic is the first deputy prime minister tasked with the role, along with overseeing the work of intelligence agencies.
An anonymous government official declined to elaborate further but said: "perhaps someone wanted to know what Vucic and others are planning about major corruption investigations".
Vucic said his relations with Socialist Prime Minister Ivica Dacic, who is also the interior minister, were good and dismissed the idea that the eavesdropping could trigger a rift within the ruling coalition.
The defence minister's allegations coincided with a row with Miroslav Miskovic, Serbia's richest man, and owner of Delta Holding, an agribusiness, retail and real estate company.
On Monday, Vucic said Miskovic and his associates wanted to topple him and his nationalist Serbian Progressive Party due to their efforts to root out corruption.
In a statement on Monday, Delta Holding said it fully supported the government which "must work in a stable political environment".