The Phuket Gazette reported that the attacker had been wearing the traditional white clothing popular with celebrants during the festival.
The 22-year-old student from Lanarkshire reported that she had been attacked on the island of Phuket.
Now police have launched a major manhunt after being told to find the attacker within seven days.
Local newspaper reports say the victim was taken to a cemetery and raped on Tuesday during the annual Vegetarian Festival.
The Phuket Gazette reported that the attacker had been wearing the traditional white clothing popular with celebrants during the festival.
The white clothing is associated with the festival's undertone of purity, moral behaviour and sexual abstinence.
The Gazette said the Provincial Police Office had launched a city-wide hunt for the rapist - after being ordered by the head of Thailand's police to arrest the man within a week.
A sketch of the attacker has also been issued from a description given by the victim.
The assailant was said to be between 20 and 25 years old, and was stronger and more solidly-built than average.
Police said the description closely matched that of a man listed in police records, and who has already served time in jail for rape.
Fire-walking ceremony
"We have 50 officers out in every corner of the island trying to locate the man," Chalit Thinthanee, Superintendent of Phuket Town Police Station, told the Gazette.
The victim was on holiday with her boyfriend and had walked into town on her own to watch a fire-walking ceremony at a local shrine.
Her boyfriend stayed in their hotel because he was ill.
The Gazette reported that the victim became lost on her way back to the hotel and was offered help by a Thai man on a motorbike.
But instead of taking her to the hotel, the man took her to a dark corner in a Chinese cemetery.
"She defended herself, but the man forced her to take off her clothes.
"He punched her on the chin once and then several times in the stomach before raping her," Captain Nakorn Sangthong of the Tourist Police is reported as saying.
The attacker then refused the victim's pleas to be taken to somewhere with lights or access to a street.
The Vegetarian Festival is a nine-day event when those of Chinese ancestry eat only a vegetarian diet to cleanse body and spirit.
The celebrations include participants who walk on red-hot coals and pierce their flesh with steel ornaments.
Earlier this year, backpacker Kirsty Jones was raped and murdered in a Thai guesthouse.
A man has been charged with her murder.