GRIMSBY'S 250 postal workers are to be balloted over changes to their pay, pensions and the planned privatisation of the Royal Mail.
Although the consultative ballot is not for industrial action, union bosses said a strike could not be ruled out if their concerns were not addressed.
The move comes as staff at the main Grimsby Post Office are preparing for a fourth day of strike action tomorrow, as part of a dispute over franchising, jobs and pay.
The Communications Workers' Union (CWU) claims that privatising the Royal Mail will threaten the Universal Service obligation, which ensures mail is delivered six days a week all over the UK for the same price – a claim which Royal Mail disputes.
The union has also raised concerns about pay, potential changes to pensions and proposed efficiency savings.
Union representatives held a meeting outside the Grimsby delivery office on Fotherby Street to update its members.
The ballot is due to take place sometime this month.
Speaking to the Grimsby Telegraph after the meeting, CWU area delivery representative Kevin Lester said: "It is important that members of the public know that if the Royal Mail is privatised it will worsen the service that they currently receive. Under the Universal Service obligation we deliver mail six days-a-week to every address in the UK. Our competitors do not do that.
"As a public company we are governed by Ofcom. Regulators do not have the same influence over private companies."
CWU branch secretary Julia West said the union was still awaiting details over pay, pensions and efficiency savings. She said: "We haven't had any clear indication on any proposed pay rise for this year. That is a concern. We also want the Royal Mail to state its position on pensions. It could depend on the privatisation.
"The ballot is to consult with our members and seek their views on these issues. There will be no industrial action at this stage."
In a statement, the Royal Mail said it was "disappointed" with the CWU's decision to hold a consultative ballot.
It added: "We have had ongoing and detailed discussions on a range of issues, including pay, with the CWU, which will continue. We are committed to seeking an agreement with the CWU on the way forward in Royal Mail that equips the business for the future and is fair for our employees."
The Royal Mail said Ofcom had ruled out any changes to the scope of the Universal Service.
'WORKING HARD TO MINIMISE ANY DISRUPTION'POST Office bosses say they will do everything they can to ensure Grimsby's main post office remains open during tomorrow's strike action. The Victoria Street branch is one of 373 Crown Post Offices across the UK which will be affected by the planned full-day walkout. Post office staff voted by nine to one in favour of strike action in a dispute over franchising, jobs and pay. The Communication Workers' Union is opposed to Post Office plans to sell off 70 of its Crown branches – those directly run and managed by the Post Office. Tuesday's walkout will be the fourth day of strike action since the ballot. The Grimsby branch was closed for half a day on both March 30 and April 19, but stayed open on April 29 when managers were drafted in to cover for striking workers. A Post Office spokeswoman confirmed that managers were likely to be drafted in again on Tuesday, but said it was too early to say if the branch would be open as usual. She said: "We will be working hard to minimise any disruption for our customers."