
The announcement came after hundreds of the red shirts submitted to Office of HM's Principal Secretary a petition to seek royal pardon for ex-PM Thaksin Shinawatra.
They also presented 500 boxes of collected signatures and their petition.
The office said that it would ask the government to review, give recommendation on the petition and report back to the office.
This is in line with the Office's normal procedures for all petitions, the announcement said.
Before the petition was submitted, Thaksin had informed his supporters gathering at Sanam Luang via video link, that he was a 'victim of injustice' and double standard.
Earlier leaders of red shirts, including senior monks, lead a march from Sanam Luang to the nearby entrance of the Royal Palace to submit an appeal to seek royal pardon for Thaksin.
The 15 leaders were allowed to submit the petition only at the Wiset Chaisri Gate of the Royal Palace. They will hand the appeal to a representative from the Office of His Majesty's Private Secretary.
The march comprised dozens of monks, followed by hundreds of red shirts who walked in the Sanam Luang compound as the Wiset Chaisri gate is just across the road from Sanam Luang.
Hundreds of red shirted people gathered at the compound since Sunday. They were told to wait in Sanam Luang compound while their leaders submitted the appeal.
The march began after Thaksin Shinawatra finished his phone-in speech from Dubai.
Wearing in red shirt, Thaksin thanked his supporters for planning to submit the petition, saying that the only one who could help bring the peace and justice to Thailand is HM the King.
Speaking to the cheering crowds, Thaksin said that the court's ruling on him regarding his former wife's purchase of Ratchadapisek Land was a really a joke.
"It is really a joke for owner and seller of the land together with buyer of the land were found not guilty on the case. But I as a husband of the buyer was sentenced to two years in jail.