The 23-year-old, who claims she was assaulted in a room near Patong Beach, in Phuket, after agreeing to go back for a party, said her attackers called her mother and told her they would rape her again unless she sent the money.
A friend described how the men placed a hood over her head and then laughed as they phoned her mother.
"She had gone back to the room with a Swede. But inside there were five others, including three Thais," the Daily Mail quoted the friend as saying.
"She was raped and then one of them demanded her mother's phone number. There was laughter as one of the gang members told her mother that unless she sent money, her daughter would be raped again.
"Afterwards she went to find the Embassy official. I don't think she could even remember her attackers and I guess she was drunk," the friend added.
It is understood that Embassy officials arranged for her medical examination, but afterwards decided it would be hopeless to attempt a prosecution.
"We can confirm we gave consular assistance in this case," a Foreign Office spokesman said.
The woman, who has left the country, had overstayed her visa and was working illegally, both crimes that carry jail terms. (ANI)