AFP, quoting Wissanu Krea-Ngam, the deputy prime minister, reported on Tuesday: "The cabinet approved the October 15 date proposed by the Election Commission as a new election date.
"It's the cabinet's authority to issue a new royal decree and there are 90 days to enable candidates to change party."
The decision was confirmed to Reuters by Yongyut Tiyapairat, the environment minister.
The election on April 2 failed to produce a constitutionally valid lower house of parliament because of an opposition boycott.
Thaksin Shinawatra, the prime minister, called the election to counter months of street protests by crowds accusing him of abuse of power and corruption, charges that he denies.
With the House of Representatives unable to meet, King Bhumibol Adulyadej intervened, summoning senior judges to his palace and urging them to sort out the mess.
However, a month after his intervention, little progress has been made.
The judges are urging the Election Commission to resign, its members are holding firm and the main opposition is refusing to talk to it.
Weeks of protests prompted
Thaksin to call the snap election
The date of October 15 was chosen to give politicians the 90 days the constitution requires for them to switch parties and run in an election, officials said.
The requirement was introduced in the 1997 constitution to prevent party-hopping, which made it difficult to form governments.
Some members of Thaksin's Thai Rak Thai (Thais Love Thais) are expected to swap parties, unhappy with his leadership despite expectations that his strong support in the countryside will return the party to power.
Thaksin took a "political break" after the last election left seats in parliament empty and the legislature unable to meet to elect a prime minister to form a government.
But he formally took back the reins of power last week.
On Tuesday, Thaksin filed a criminal defamation lawsuit against a newspaper of a former business partner who started the street campaign, Thaksin's chief lawyer said.
Thaksin, who dropped libel claims of $50 million against the same newspaper and its founder last year after the king chastised him publicly for filing them, planned similar actions against other opponents, Thana Benjathikul said.
He would file two more criminal libel cases, which can carry jail sentences, against a group of academics and a group of senators, and a $26 million civil libel case against all three groups on Friday, Thana said.