Unions have slapped down Danny Alexander's 'take it or leave it' deal on public sector pensions. Despite the chief secretary to the Treasury announcing significant concessions ahead of planned strikes at the end of this month, in a statement TUC chief Brendan Barber said unions were still "firmly committed" to strikes.

"Unless and until further real progress is made and acceptable offers are made within those negotiations, unions remain firmly committed to continuing their preparations for the planned day of action on November 30", said Barber.

Earlier on Wednesday Alexander outlined an 8% increase on the government's previous public sector pension settlement, adding that no worker within 10 years of retirement will need to worry.

Negotiations on changes to public sector pensions have been going on since February 2011. The government has always insisted that the meetings with union leaders have been 'productive' but the unions themselves have consistently said that ministers have failed to give any ground on their demands.

"No public sector worker needs to have anything to fear at all for any of the entitlements they have already built up," Alexander said.

"No one within 10 years of retirement will see any change in when they can retire or any decrease in how much they can receive."

He challenged the trade unions to "grasp the opportunity" of the new offers.

"We've listened to the concerns of public sector workers and come up with a deal that is fair and affordable."

"I hope that on the basis of this offer, the Trade Unions will devote their energy to reaching agreement not on unnecessary and damaging strike action.

"That way this offer can inform the scheme by scheme talks that will continue until the end of the year. Of course, if agreement cannot be reached we may need to re-visit our proposals, and consider whether those enhancements remain appropriate."

The GMB's Brian Strutton also said they would continue to hold ballots, saying in a statement on Wednesday: "My view is that we would want to explore the effect of the improved offer whilst still seeking answers on the outstanding matters. We will not be able to resolve these issues quickly or easily so our industrial action ballot continues as will negotiations."

Public and Commercial Services union general secretary Mark Serwotka said: "Any new offer is always welcome but the latest concessions are only marginal and would still force public servants to pay more in and work longer for less in retirement.

"Effectively ministers are saying they will only raid pensions by slightly less than they were planning to. The money raised will still go straight to the Treasury to pay off the deficit, not into pension schemes that have been shown to be affordable now and in future.

"It is not true that people close to retirement age will be protected, because they will still be forced to pay up to three times as much for a pension already devalued by up to 20% by the imposed switch in indexation which we have challenged in the High Court.

"It should be remembered that this latest offer was only wrung out of ministers by the threat of mass industrial action on 30 November, and following our successful strike with other unions in June.

"We will look at the details to see how they affect our members, but we continue our plans to make 30 November the biggest strike we have ever seen.

"It remains to be seen if ministers are prepared to stop tinkering around the edges and start talking to us about the core issues of concern for millions of public sector workers."