Georgian prosecutors released a tape filmed in secret that purportedly shows Patarkatsishvili offering $100-million to Erekle Kodoua, a senior interior ministry official.
The money was allegedly in return for control over police forces in the days following the snap election, held on January 5.
According to the prosecutor's tape, which Patarkatsishvili labelled as a fake, Kodoua was to reveal "evidence" of ballot stuffing by authorities, arrest Vano Merabishvili, the interior minister, and take control over the country's police forces on the day after elections.
'Mass disorder'
The tapes allegedly show Patarkatsishvili's campaign chief, Valery Glebakhiani, saying: "On January 6 there will be mass disorder ... That the elections would be invalidated, which would set the stage for a coup."
Patarkatsishvili has previously accused the Georgian government of fabricating charges to apply political pressure on him and his associates.
A flamboyant businessman who earned a fortune in Moscow as the Soviet Union collapsed, Patarkatsishvili initially supported Saakashvili when he came to power in 2003 on the back of the 'Rose Revolution' protests.
But Patarkatsishvili later turned against the US-educated lawyer and played a key role in bankrolling the opposition, which he has said he will continue to finance.
Western monitors have said the January 5 election was slightly flawed, but still competitive.