The Scottish Government has been challenged to find more cash to end a pay dispute which has seen rubbish pile up on streets across Scotland.
He made the plea as talks continued over the weekend between trade union leaders and Cosla, the organisation that represents Scottish local authorities.
The first wave of strikes saw cleansing staff in Edinburgh walk out on August 18, with the action in the capital coinciding with the busy festivals period.
With no deal yet to end the dispute, action spread last week, with the majority of councils now impacted by similar strikes.
Bosses at Public Health Scotland have already warned the build-up of waste could “become a risk to human health”, telling councils that “decontamination of public areas where bins have overflowed may be required”.
Mr Sarwar backed demands from trade unions for local government workers in Scotland – who have so far been offered a 5% pay rise – to get a similar increase to the £1,925 offered to council staff in the rest of the UK.
While the Scottish Government has already given councils an extra £140 million to increase workers’ pay, Mr Sarwar insisted ministers needed to contribute more.
Without further cash from the Government, the Labour leader said the shortfall would have to be met by “councils having to cut their budgets even further”.
Speaking on BBC Radio Scotland’s The Sunday Show, Mr Sarwar said: “The Scottish Government, yes they put £140 million in to support the uplift. But rather than cutting council budgets more I think they need to find more money.
“If they have a longer term financial challenge they can make a one-off bonus payment to build up that money.”
Funding identified in the Scottish Government’s emergency budget review could be used, the Labour leader suggested, along with some of the “hundreds of millions of pounds of reserves” that ministers have.
Mr Sarwar said: “They also have that secret money hidden at the back of the sofa that they normally pull out every time there is a budget deal to be had or when they want to announce their own pet projects.
“Let’s have transparency, accountability, find the cash, pay these workers properly, get workers back to what they want to do, working and not being on strike and cleaning up our cities and towns across this country.”
His accused the Scottish Government of having slashed £6 billion from local authorities’ budgets since 2013-14.
“Even in the David Cameron austerity years, when the Scottish budget went down by 4%, they were tripling that and giving a 12% cut to local government,” Mr Sarwar said.
“This is a national dispute and the SNP, the Scottish Government, the SNP-run Cosla, have a duty to support these workers.
“What I hope we will see today is the unions getting what they have been demanding. I support this campaign that we have a flat rate that is similar to the increase they are getting in England, so around £1,900.
“Rather than giving 5% to every worker across the board that would target support to the poorest and the lowest earning income holders in councils.”