The new head of Police Scotland has been officially sworn in, praising what has been achieved at the force but insisting there is "still more to be done".

Phil Gormley, former deputy director of the National Crime Agency, has taken over as chief constable from Sir Stephen House, who stood down at the end of November after three years in the job.

Following a ceremony at Tulliallan police college, Mr Gormley said: "I'm acutely aware of the significant responsibility and expectation that comes with the role of chief constable.

"It's an honour to have been selected to lead Police Scotland."

He added: "Today I met officers who, like me, are starting their careers with Police Scotland.

"Over the next weeks and months, I will be talking and listening to not only Police Scotland officers and staff but also our partners to help inform how we respond to the challenges the service faces.

"Much has been achieved in the first few years of Police Scotland but there is still more to be done - and I recognise the importance the public and partners place on the level of service we provide.

"There is no doubt we are in a challenging financial environment - despite the savings already made, it is my responsibility working with colleagues to deliver the best service possible with the available resources.

"This will require difficult decisions but I am determined that we will develop a service the public trust and have confidence in and which our officers and staff are proud to provide."

The appointment was made on the recommendation of the Scottish Police Authority (SPA) and was approved by Scottish ministers.

SPA chairman Andrew Flanagan said: "The appointment by the SPA of Phil Gormley as chief constable of Police Scotland is a key part of the next phase of change for policing, and we welcome him taking up the reins this week.

"We have secured the best candidate to build on the progress that policing in Scotland has already made, and to address the issues and challenges that the service faces.

"The recent budget announcement by the Scottish Government demonstrates welcome support for police funding next year and provides an encouraging base on which the SPA and the new chief constable can build.

"With the SPA governance review also due to report in March and the Scottish Government consulting the public on policing priorities, there is now a major opportunity in the early part of 2016 to shape the future direction of policing with the active participation and involvement of the police workforce, partners and local communities."

Justice Secretary Michael Matheson said: "I am confident that Mr Gormley will bring a strong, positive influence to the next stage of building an organisation that is focused on best meeting the needs of the communities that it serves and that has local policing at its heart.

"I look forward to working with him and the Scottish Police Authority to continue to develop a service that is representative, accountable, and fit for 21st-century Scotland."

Over the course of his 30-year career, Mr Gormley has been deputy chief constable of West Midlands Police and a Metropolitan Police commander. He was awarded the Queen's Police Medal in 2012.

Sir Stephen, who oversaw the merging of eight forces to create Police Scotland, stepped down at the start of December amid criticism over a number of high-profile issues including stop-and-search and the force's handling of the M9 crash near Stirling last July that left two people dead after officers took three days to respond.