Ipswich council has been threatened with another legal challenge – this time from some of its lowest-paid workers who claim they have been denied a pay rise by their bosses.

The borough’s 21 street cleaners have enlisted the help of the town’s Conservative MP Ben Gummer as they try to ensure they get pay rises they have been awarded over recent years.

The cleaners’ wages are among the lowest at the borough and have been linked to the minimum wage so when that goes up their pay should rise.

However they also receive an “attendance allowance” on top of their wage – and this has been lowered every time their wage has increased over the last five years, effectively meaning they have received no pay rise.

Aidan Connolly said: “When I started in 2006 I got an attendance allowance of £34 a week, now it is down to £23 a week. That means over the last few years I’ve lost about £1,500.”

The cleaners’ Unison representative had raised the issue with the management, but Mr Connolly said this had not been successful. “I was told it might be immoral but they were able to do it,” he said.

They took their plight up with Mr Gummer who sought the advice of a top employment solicitor in London.

Jill Andrew, of Beamlaw, wrote to him saying: “I consider that your constituents have good grounds on which to pursue legal action against the council.”

Mr Gummer said: “These are some of the lowest-paid workers in the town, getting about £16,000 a year, and the council has taken away the pay rises to which they are entitled.

“The council seems to think just because they are doing a dirty job that they must be too stupid to see what is happening to them!”

The street cleaners had originally not wanted to go public on their concerns, but they were now preparing to launch a legal challenge.

A borough spokesman said: “The council has not formally received any legal correspondence from Ben Gummer’s office on this matter.

“While there was an issue over the pay of cleansing staff this was fully resolved via agreement with Unison following a ballot of their affected members with effect of April 1, 2014.

“There are no outstanding issues. It is not appropriate to comment further.”

The new legal threat to the borough comes just days after the county council threatened to seek a judicial review of a borough planning decision over payments for new school places.