In a letter to MP Keith Vaz, chairman of the Home Affairs Committee, solicitors representing husbands of two of the three sisters, alleged that officers from the North East Counter Terrorism Unit (NECTU) were "actively promoting and encouraging" the sisters to contact their brother thought to be fighting in Syria.
They said that there was "reckless disregard" for the consequences of any such contact on the families," the BBC reported.
They also said that were "extremely disappointed" with the way the case had been handled.
West Yorkshire Police, however, completely rejected the allegations.
Also Read
"We completely reject accusations that the police were complicit in the alleged grooming of the missing family or that we were oppressive to them," Assistant Chief Constable Russ Foster said.
Three sisters from the city of Bradford -- Khadija, Sugra and Zohra Dawood -- went missing with their nine children while travelling to Saudi Arabia to take part in a religious pilgrimage.
They were reported to have travelled to Syria to join their younger brother Ahmed, who is believed to be fighting with extremists in the country.
NECTU said it was "continuing to make extensive enquiries" in order to try to bring the women and children home.