City streets could end up filthy again because of yet another dispute between collection firm Sita and its staff.

Union bosses said the workforce could not meet new demands imposed by management to keep the streets clean.

Mark Turner, of the GMB union, said new street cleaning schedules to be introduced on Monday were "utterly unrealistic" and many staff would be forced to ignore them.

He said: "It is the people who live in the city who will suffer over this.

"We know the schedules have been changed but the workforce has not been consulted at all.

"We've not been told how many men make up a crew, why they have to change and what is expected of us."

But Sita said the changes would make the routes easier to control and bosses would be meeting with staff to discuss the new routes later this week.

The schedules cover the eastern parts of the city district, including Moulsecoomb, Bevendean and Saltdean.

Mr Turner said street cleaners had complained to their union because Sita had created the routes without taking the nature of the roads into account.

He said: "These new routes are based solely on how long the streets are.

"They don't look into whether there are grass verges, pavements or gutters and how much time it takes to clean roads properly. Every street is being treated the same, which is not the way to do a proper job."

The length of roads on the schedules ranges from about 12.5km, which includes Elm Grove, to cleaning a 2km stretch of Madeira Drive.

Mr Turner said different streets needed different methods such as mechanical sweepers or handbrushing.

He said: "This is all bean-counting.

"It seems like they've just looked at a map and not bothered going out to see what the roads are really like.

"One road could take half an hour to clean whereas another one of exactly the same length could take half a day depending on the method used.

"There have been all the problems of the past year and now they have changed it again. How is the workforce meant to keep up? We cannot rule out any protest action at the moment."

The refuse collection and street cleaning service in Brighton and Hove was plunged into chaos last summer after changes were made to collection days. Sita then said the system would be more effective because street cleaners would follow refuse collections. The service was disrupted for weeks and sacks of rotting rubbish filled the city streets.

A spokeswoman for Sita, which operates on behalf of Brighton and Hove City Council, confirmed the changes would come into effect on Monday. Street cleaning in west and central areas will remain unchanged.

She said: "The changes will establish definable routes that can easily be controlled.

"We are arranging to meet workforce representatives later this week to discuss the changes. They will be brought into force on Monday."

A spokeswoman for Brighton and Hove City Council said it was discussing the changes with Sita.

She said: "The idea behind this is to make the responsibilities of individuals and crews clearer so we know who should be cleaning which street when.

"This has not been designed to make the job harder."