Two new assistant chief constables have been appointed to Police Scotland as four officers face an investigation into allegations of criminal and gross misconduct.

The force announced on Friday assistant chief constable Bernard Higgins and three colleagues had been suspended over the claims, while a further two officers have been placed on restricted duties.

The Scottish Police Authority (SPA) has now appointed two temporary assistant chief constables in a bid to shore up Police Scotland's command structure.

Chief superintendent Gillian MacDonald will be responsible for major crime, local crime and public protection, while chief superintendent Alan Speirs will be responsible for professionalism and assurance.

Both officers have successfully completed the Strategic Command Course - a prerequisite for officers of assistant chief constable rank and above.

Deputy chief constable Iain Livingstone announced the appointments at an SPA meeting in Stirling on Tuesday.

He said: "This is clearly a challenging time for policing in Scotland and my focus continues to be on meeting the operational and organisational challenges we face, and providing the leadership of policing that the people of Scotland rightly expect.

"I remain in charge of day-to-day policing, strongly supported by my colleagues in the force executive, together with the command teams in every part of local policing in Scotland, as well as specialist national departments."

Chief constable Phil Gormley remains on a "leave of absence" two months after allegations emerged of possible gross misconduct.