The SNP are "illiberal, centralising, arrogant and increasingly incompetent", the Scottish Liberal Democrat leader has claimed in a rallying speech ahead of Scottish Parliament elections.

Willie Rennie said Nicola Sturgeon's party would use any excuse to talk about anything but their public service failures at home.

Speaking to the Liberal Democrat conference in Bournemouth, Mr Rennie said the failure of Police Scotland to find a young couple who crashed off the motorway for three days epitomised the failure of the SNP administration.

The SNP merged all of Scotland's police forces into a single body in 2013 despite protests from political opponents it would damage services.

Mr Rennie said: "It is shameful that it took the deaths of John Yuill and Lamara Bell to force them to act. This shows more than any other single issue that there is something wrong at the heart of the SNP Government.

"They were warned. They should have known. They should be ashamed.

"There is no hyperbole in what I now say. If it were not for the small team of determined Liberal Democrats in Holyrood the SNP would go unchallenged on the police, on justice and on the protection of our civil liberties.

"The SNP are an illiberal, centralising, arrogant and increasingly incompetent government who have put their party before my country for far too long."

Mr Rennie told activists there was a shortage of GPs in the Scottish NHS and "neglected" mental health services, while in schools literacy and numeracy standards were falling.

He said: "Children at school today have only ever had the SNP running their schools. But SNP ministers behave as if it's their first day in charge.

"It isn't. Their eye has been off the ball for years."

The Scottish party leader said his team of five MSPs was "punching above its weight" as it bids to rebuild following severe losses in 2011. That election saw an improbable SNP majority in Holyrood and paved the way for last year's historic independence referendum.

Mr Rennie said the SNP was picking fights with the BBC and talking up the prospects of a second referendum rather than concentrating on the domestic agenda.

He said: "The election next May should be about the way they are running things in our country, in Scotland.

"The SNP want the lights to be turned off on scrutiny of their domestic record. We must not let them get away with it."