A union has described a 5% pay offer to council workers as a "vague aspirational pledge" as it pledged a continuation of the first wave of local authority staff action involving waste collectors.

It comes as the Scottish Government was urged to intervene and “prevent international embarrassment for Edinburgh and Scotland” as an initial strike by council staff left litter bins overflowing in the capital.

Tories and the Liberal Democrats both demanded action, although First Minister Nicola Sturgeon has said she hopes the improved pay offer will be sufficient to end the “disruption” in Edinburgh.

But the union Unite indicated that it was not.

Alison Maclean, Unite industrial officer, said: "Unite’s local government committee has reaffirmed that the strike action ongoing in Edinburgh and scheduled to take place in a further 14 councils continues as planned.

"There remains insignificant detail on the five percent pay offer, and what this in reality means for the lowest paid workers. At this moment the offer from COSLA  [the Convention of Scottish Local Authorities] remains a vague aspirational pledge but Unite can’t take anything to our wider membership unless we have specifics and guarantees."

She said a meeting was scheduled for Tuesday with COSLA and that the union will then reassess the situation.

"Our members have taken the brave stance of taking strike action to get the pay rise they deserve and we are determined to ensure that this happens, she said.

 GMB Scotland senior organiser Keir Greenaway also called for clarity over whether the proposal comes with the assurance of a flat rate award, a key demand of the union pay claim.  

“The prospect of the highest paid getting the biggest cash increases in any offer would be unacceptable, let alone one that is still well below inflation.

“Unions will now meet with COSLA officials tomorrow morning, but in the meantime all existing and planned strike action remains on.”

The pay offer that was made on Friday had involved setting the minimum hourly rate to £10.50.

Unite has previously criticised COSLA - which acts as an employers' association - for taking over five months to make an offer than could be put to members.

It comes as images emerged on Monday morning of rubbish piling up on the streets of Edinburgh as a result of the strike.

The walkout in Edinburgh, the first in a series of protests planned by trade unions, is due to go on until August 30, with bins around the city already overflowing with rubbish as a result of not being emptied.

The strike is due to be escalated to the other councils on August 24 and 31, unless there is a resolution to the dispute.

It is estimated that around 1,500 Unite members across 15 councils will join their colleagues in City of Edinburgh Cleansing and participate in the second wave of strike action. Unite will be the only union involved in this phase of council strike action.

Three unions, the GMB, Unite and public services union Unison say they have received a mandate for strike action in a local government pay dispute over a dispute over the initial 2% pay offer to Scottish council workers which could lead to the shutting of shut schools.

COSLA  - has been warned by the unions Unison, GMB and Unite that it has a mandate to disrupt schools in 16 of Scotland 32 local authorities.

Unions had said targetted strikes could take place as early as mid to late August after pupils return from the summer break.

The action comes while Edinburgh is the “centre of the cultural world”, the First Minister said.

Ms Sturgeon said: “Nobody wants to see the kind of disruption and impact of strikes that many people are witnessing in Edinburgh right now.”

But she said she hoped the improved pay deal, which would see wages increase by 5%, would resolve the dispute.

Terry Levinthal, director of Edinburgh’s heritage watchdog the Cockburn Association, warned that the city faced “a massive public health problem” and that vermin levels were expected to increase, with scavenger seagulls already out in “full force”.

“Even before the strike there were problems,” he said.

Miles Briggs, a Scottish Conservative MSP, has meanwhile rebuked the city’s Labour council for an “astounding” lack of contingency planning.

“More could have been done to prepare the city, such as working with private companies or providing additional bins. The SNP Government must now intervene to prevent international embarrassment for Edinburgh and Scotland.

The local government body, COSLA, made the latest offer on Friday, and while unions have said they will consider the deal they warned it is still significantly below the current rate of inflation.

Alison Maclean of Unite noted: “While the 5% offer is an improvement, it is important to emphasise that it comes at a time when the broader retail price index has now hit a 40-year high at 12.3%.

“Unite’s local government committee will urgently consider this latest offer. At this juncture the strikes for next week continue as planned.”

Scottish Conservative local government spokesman Miles Briggs, however, said there had been an “astounding” lack of contingency planning ahead of the strike, saying: “More could have been done to prepare the city, such as working with private companies or providing additional bins.”

With bins having not been emptied for several days, he said: “The SNP Government must now intervene to prevent international embarrassment for Edinburgh and Scotland.

“The rubbish piling up on our streets risks damaging our city’s reputation.

“These annual festivals are supposed to be a source of pride, not humiliation."

The pay uplift is funded jointly by local authorities and the Scottish government.

COSLA said council leaders would need to discuss council support with the government to ensure long-term funding and flexibilities to limit the impact on public services and communities.

The Scottish government previously said it expected local authorities to match the £140m extra pledged by the Scottish government for pay rises.

Local government minister Shona Robison called the increased pay offer a "welcome step forward".