The union is holding a two-day policy forum in London next week, and if a resolution for a strike ballot is passed by the 500 reps, and the union’s 115,000 Royal Mail members vote in favour, industrial action could begin as soon as the end of September.

If the ballot does go ahead and is approved, which based on the results of the union’s consultative ballot last month seems likely, any strike action is likely to clash with the planned privatisation of the Royal Mail.

CWU head of communications Kevin Slocombe said that a final decision on whether to ballot Royal Mail members would only be made if no agreement was reached or if the ongoing negotiations with Royal Mail were deemed unsuccessful.

Talks with the Royal Mail began this week and are scheduled to run for three weeks. If no agreement is reached, a 21-day ballot could be launched in early September. However, Slocombe added that even if the current talks fail and a ballot is launched, this wouldn’t rule out further talks with Royal Mail.

Billy Hayes, CWU general secretary, said: "UK postal services are facing unprecedented change and threats. We will always embrace innovation and changes in the industry, but only on terms which maintain decent jobs and protect quality services.

"This policy forum is all about anticipating what may lie around the corner and how CWU can react to protect the interests of our members and customers they serve in the increasingly changing world of postal services."

Issues to be discussed at the policy forum will include securing job "protections" in Royal Mail, alternative business models to privatisation, changes to pensions and workplace pressure.

Dave Ward, CWU deputy general secretary, said: "We want to secure the best possible protections for our members’ jobs and we will stop at nothing to ensure that their future, and that of the UK’s postal services, is protected.

"The offer on job protection made by Royal Mail earlier this month wasn’t worth the paper it was written on. Patience is wearing thin and unless we can secure robust protections for jobs, pay and terms and conditions soon we are asking our reps to endorse a policy of holding a national industrial action ballot no later than September."