A total 29 fuel thefts across the region since January 6 are linked, Humberside police believe.
A Transit style van has been used to steal over £3000 of fuel from petrol station forecourts in each of the cases.
This has occurred around Scunthorpe as well as Hull and Grimsby, and 15 took place in the East Riding.
Police strongly suspect at least two Transit style vans have been used across the force to commit the fuel thefts, one being a white Transit style van and the second being silver coloured.
On all occasions van drivers have approached the forecourt of the petrol station, filled up and driven away without offering payment. A variety of false plates were used.
An unusual feature is that the majority of incidents took place in tandem.
Officers are working across the force in an attempt to try and locate the offender(s). It is not known where the stolen fuel is taken although it is likely to be sold on.
Petrol station staff are working with police in a bid to target those who are responsible.
Anyone who may have information in connection with these crimes should call Humberside Police tel 101 and quote log 156 of 06 January 2014.