At least three trade unions are set to demand pay rises from the Scottish Government which will be higher than inflation, STV News understands.

One senior trade union official has told STV News that a rise as large as 5% is a reasonable request.

A series of pay negotiations with the Scottish Government will begin shortly ahead of the administration's budget in December, but no progress is expected to be made until the UK Government's budget is announced in November.

The First Minister has promised to lift the 1% pay cap in a speech in September when she outlined her government's programme.

Inflation is currently running at 2.9%, with food and fuel prices being pushed up after the decline in the pound's value since the EU referendum.

Scottish Trades Union Congress deputy general secretary Dave Moxham told STV News: "I think we'll be talking tough to both governments but I think that the fact that the Scottish Government now has aditional tax powers, the fact that it's indicated that it's now prepared to at least consider using those, is bound to send a message both to the people who use services but also to the people who deliver those services."

In September, the First Minister said the current cap is "not sustainable" due to the rise in inflation.

The UK Government is also set to give pay rises beyond the 1% cap for the first time since 2009.

The vast majority of the Scotland's public service workers are employed in the devolved sector, with the Scottish Government therefore responsible for their pay.

When asked about the unions' demands, finance secretary Derek Mackay told STV News: "I will set our pay settlement at the Scottish budget later this year, I have set a date for that.

"And what I have said [is] I will take into account is the inflationary pressures which have of course impacted upon public sector workers."

Mackay said how big the pay rise will be is "partly determined by what the Chancellor does in his budget".

The Scottish Government could face industrial action if trade unions are not satisfied with Mackay's offer.

The finance secretary downplayed the possibility of strikes as he believes both sides already have a good relationship which "should ensure we continue to have constructive dialogue with the trade unions and they appreciate we can go further if the UK Government and the Chancellor acts in a way to support public services across the UK in a fashion that we want to in Scotland."

You can read more about this story on Scotland Tonight at 10.35pm.