Speaking in Pretoria yesterday, Sisulu asked organised labour to return to the negotiating table but the unions said the minister was the one stifling the wage talks by giving them 21 days to sign the final offer of 6.5% that she put on the table on Wednesday last week.

Chris Klopper - chairman of the Independent Labour Caucus, which represents 11 unions with a total of 480000 members - said the caucus had declared a dispute to force the government back to the negotiation table.

He said this meant that a mediator would have to be appointed within 30 days to get the two parties to reach an agreement.

He said that, by giving the unions an ultimatum, Sisulu was saying: "Take it or leave it."

"We're not interested in her offer and we told her that we are not going to sign," he said.

But Sisulu said she was committed to the wage talks.

"Unlike what the media have said, they will find that I have no horns; there is no devil in me. It is also in their [the unions] interest that we find an amicable solution," she said.

The unions have demanded an 8% wage increase and a R1000 housing allowance. But Sisulu wants to increase the current R800 housing allowance to R900, which she said would soon be converted into a subsidy on a housing bond.

The Public Servants' Association said it could not agree to the R900 housing allowance because it was still considering it .

The association's general manager, Danny Adonis, said the scheme would benefit only those who qualified for a bond and would disadvantage those who did not.

Adonis blasted Sisulu for "negotiating in the media".

According to Sisulu, the offer the government had made amounted to a 9% increment - a 6.5% wage increase and a 2.5% increase in benefits such as medical aid, pension funding and housing allowance.

She said this would cost the government R30-billion a year - and the Treasury had budgeted for an increase of only 5%.

Sisulu said this amounted to R8.1-billion more than had been budgeted for this year, so the government would have to dip into its reserves to meet the wage bill.

She said the public service wage bill had risen sharply - from R211-billion in 2009 to R314.9-billion last year.

"Any unrealistic settlement will impact on the pro-poor policies. It will be taking away something we have been giving the poor, taking away from infrastructure investment and taking away from the possibility of job creation," Sisulu said.

She said South Africa was among the few countries to have weathered the global economic crisis, but she did not know "how long we will be able" to do so.

She said she hoped labour would be reasonable in light of the global economic crisis.

Sisulu added that government was sensitive to the needs of labour.

"We just have to balance it with the needs of our people in a time of global economic crisis," she said.

Many unions have welcomed the Public Service Charter proposed by Sisulu, which calls for salary increases to be based on productivity and performance. But the unions said they would have to study it closely before signing it.