The men, who have been pictured on CCTV wearing wigs and women's clothes, allegedly charmed their way into pensioners' homes in York and Harrogate by posing as officials from a bank or utility company.
Detectives say the suspects were "charming and friendly" as they convinced elderly people to part with their bank cards and pin numbers, claiming their account had been defrauded.
They then offered to send someone to the victim's house to pick up their bank card to help them to sort out their account.
But they used the details to withdraw large sums of money from banks and travel agencies and to buy goods, North Yorkshire Police said.
Detective Sergeant Lydia Davenport, of Harrogate CID, said: "There are a number of suspects involved who go to some lengths to disguise their identity, including dressing up as the opposite sex.
"These people are very plausible and charming when they contact the elderly people and it is easy to see how they can be convinced by what they are saying.
"We are determined to catch them and bring them to justice. I am therefore asking for the public's help as we continue our investigations."
Police said they are still investigating whether the conmen were dressed as women when they visited their victims, or whether it was purely a ruse to evade detection when they withdrew the money.
A North Yorkshire Police spokesman said five offences were reported in Harrogate and two in York last month and this month, and urged anyone who recognises the suspects or has seen anything suspicious to contact them.