Chief Constable Sir Stephen House has come under renewed pressure as his rank-and-file cheered a politician's warning that he "needed to change his ways".

The most powerful officer in the history of Scottish policing began his third year in charge of the national force facing both a budget crisis and intense political criticism over his handling of stop-and-search.

Opposition leaders piled rhetoric on to Sir Stephen at the first conference of the Scottish Police Federation since the new Police Scotland bedded in.

Willie Rennie - the Liberal Democrat leader and a fierce critic of the single force - was the most outspoken, prompting guffaws and whoops from SPF members when he attacked what many in the force believe is a targets-culture.

Mr Rennie told SPF members: "The integrity and trust in the leadership of Police Scotland is on the line.

"Too often we have been told one thing, for another thing to turn out to be the truth.

"The Chief Constable said that no guns would be carried by officers on routine duties. Not true.

"And he said there was no target-driven culture. You all know that is not true."

"He needs to be straight - with us, with you, and with the public.

"He heeds to have clarity, he needs to be honest, he needs to be truthful, he needs to change his ways."

Mr Rennie has fare from always seen eye-to-eye with the SPF. But only Fed insider said: "You can't lose by criticising a boss at a workers' conference."

The SPF last met in 2013, early in the existence of the single force. Members made it clear they were not happy with Sir Stephen.

To roars of approval from the conference a sergeant , Scott Meechan, asked First Minister Nicola Sturgeon what he called "the football manager question".

Mr Meechan said: "After disappointing results, football clubs often deliver the dreaded vote of confidence in support of their manager. This is often swiftly followed by a change of manager with the manager moving on by mutual consent.

"The First Minister recently stated she had full confidence in the chief constable. Should Team Police Scotland expect a new manager?"

Ms Sturgeon replied: "There is no way to rightly answer the football manager question.

"I have confidence in chief constable and I think the police should have confidence in the chief constable and more importantly than that, I think the public should."

To murmurs of approval from her audience, she added: "No chief constable is or ever can be or can ever be allowed to e a law unto himself. That is absolutely the position.

"Like anybody who holds this position, the chief constable will reflect on some of the discussions and debates and disagreements we have seen in recent months and reflect very openly."

Ms Sturgeon clarified that she did not think Sir Stephen was a law unto himself.

Jim Murphy, who was also speaking at the conference, said he did not know Sir Stephen well enough to call for his head. But, stretching the football metaphor, the Scottish Labour leader said: "I think he should do his talking on the field. I will judge him by his results, not his media."

Conservative leader Ruth Davidson spoke out against Strathclyde tactics being spread across Scotland.

This has been a recurring theme in Scottish policing, and was stressed by many SPF members, although many see the tactics as belonging to Sir Stephen's previous force, the Met, rather than Strathclyde.

Tayside constable Sandy Smart said: "We are now policing the way the Met did 10-15 years ago. And we know how they have lost touch with communities."

Many, including Deputy General Secretary David Kennedy, expressed fears that overuse of so-called consensual stop-search, where a member of the public is asked to voluntarily submit to a search, threatened the future existence of the power. Mr Kennedy said: "We may be throwing the baby out with the bath water."

Politicians have been critical of Sir Stephen before with many in Police Scotland believing the force had become a political football.

Stop-searches, for example, peaked before the single force - but only became a big issue after it was formed, thanks, academic Kath Murray told the SPF conference, to "policing become political".

A spokesman for Sir Stephen again linked remarks by the MSPs to big politics.

He said: "While the General Election campaign may be underway, we published our 3rd annual police plan today, focusing on what communities across Scotland want from Police Scotland. We will carry on focusing on that."

The SPF chairman, Brian Docherty, meanwhile had opened the day by warning of an elephant in the room: budget cuts.

Sir Stephen on Tuesday warned of "extreme measures" to balance the budget and complained his force was the only one in the UK to pay VAT, some £24m a year.

Ms Sturgeon said she would fight that issue and pledged to maintain police numbers and conditions. She was joined in that last pledge by all three other party leaders.