The red shirts from Ayutthaya will travel by more than 100 boats prying the Chao Phya to join the mass rally on Sunday, Pheu Thai MP Surachet Chaikosol said on Thursday.
An advance team will start arriving in Bangkok on Saturday but the main procession of long-tail boats and barges will begin the following day, he said.
The red shirts plan to their landing at Ta Phra Chan pier, he said. The pier is located next to Siriraj Hospital where His Majesty the King is staying.
