"Their demands for money are a form of taxing, which is completely illegal. We are also very concerned about the levels of violence these gang members are using against the sex workers.
"If there is an emerging problem in the local sex worker community, then we need to know about it."
Napier brothel owner Kathy Woods, who has worked in the sex industry for 30 years, said prostitutes working for gang members was "nothing new".
"This has been going on for years and years," she said.
"I do know we've had young girls working for us and they end up working for gang members, and we don't see them again."
She said the gangs targeted young girls in particular.
"When the gangs get hold of these girls they get hooked into the drug scene.
"As soon we we get a young girl working for us, she's only there for a few weeks and then she's gone.
"They should change the law slightly so these girls are more protected than what they are. Any private escort should be registered," Ms Woods said.
But New Zealand Prostitutes Collective (NZPC) national co-ordinator and sex workers' rights activist Catherine Healy said reports of gang members trying to extort sex workers were uncommon.
"We don't have evidence that gangs are running sex workers in any sustained way."
A sex worker spoken to by Hawke's Bay Today, who wished to remain anonymous, said she had not been approached by gang members and was not aware of it happening to others.
Mr Foley said some sex workers may be reluctant to speak to police, but there were other options available to them such as the NZPC.
"It's very important that we are told about these incidents, not just because of the illegal nature of this activity, but also because of the danger these women may be in. Any forms of violence are unacceptable, especially when people are being pressured or threatened."
-Any sex workers who have had similar experiences are urged to phone Mr Foley at Hawke's Bay Police: 06 831 0700.