Around 90% of workers at the South African Post Office could go on a two-day strike next week, the Communication Workers Union (CWU) has warned.

Sapo employees have not received salary increases for two years, the head of CWU Clyde Mervin told Fin24 by phone.

Subsequently, CWU is planning a strike for May 5-6 to demand higher annual pay rises for Sapo staff and the conversion of casual workers to permanent employees, said Mervin.

The planned strike comes despite the Post Office currently being cash-strapped as it reported a R1.5 billionn loss for the 2015 period. Sapo employs around 22 000 staff.

"For two years no increase - so workers have been saying enough is enough,” Mervin told Fin24 by phone.

"Casual workers have been working for 20 years with no permanent employment - when are we getting these things right?"

"We have marched to government, we have marched to African National Congress (ANC), we have marched to the post offices and we are saying we are going back to the streets, purely because government officials have received increases consistently,” said Mervin.

Sapo is undergoing a turnaround phase as government moved late last year to hire former banker Mark Barnes as its chief executive officer.

Barnes told Parliament earlier this year that Sapo could be profitable again by 2018.

Despite Sapo being in the early stages of its turnaround phase, the CWU says it’s still going ahead with its planned strike to hit out at previous maladministration and corruption.

Public Protector Thuli Madonsela in February found that Sapo’s acquisition of a R161 million ten-year lease in 2010 for an office building in Centurion, Gauteng was “tainted by procurement irregularities and corruption”.

“Management were totally corrupt as far as we were concerned and obviously we are still waiting for the SIU (Special Investigative Unit) report to clarify other issues," Mervin told Fin24.

Government earlier this year also gave Sapo a R650 million bailout but CWU’s Mervin said this too little.

Mervin also hit out at Sapo CEO Mark Barnes.

"We met with Barnes last week... Barnes has got total no respect for unions. The way he spoke to us; the way he treated us - it's like we are nothing to him,” said Mervin.

"We are going to give him time to fix the Post Office but he must change his attitude towards workers and towards the union leaders,” Mervin added

Post Office CEO Mark Barnes reacts

Meanwhile, Sapo CEO Mark Barnes said CWU’s announcement of the strike has come as a surprise.

"We haven't even got notification of the strike yet. I think at this stage it's positioning,” Barnes told Fin24 by phone.

Barnes further told Fin24 that Sapo is in the final stages of raising capital from the likes of banks to fund its turnaround, and that a strike is not "in the best interest of the workers at Sapo”.

"If you upset this apple cart now, it might be the last time you upset it,” said Barnes.

"If we give them (funders) any reason to go away, they will,” Barnes added.

The Sapo CEO further said that he hopes to avert the strike. If the strike goes ahead, Barnes said he also wouldn’t turn to the courts to try and interdict it.

"I need to demonstrate responsible forward-looking behaviour and move away from conflict towards negotiation, settlement, common-purpose,” he said.