Scottish police officers are to demand a 15% pay rise at their federation's annual conference next week.

Members of the Scottish Police Federation (SPF), which represents more than 16,000 police officers in Scotland from constable to chief inspector rank, will forward the motion at the Peebles conference that will be attended by the Justice Secretary.

Other motions include calls to discuss the "apparent lack of accountability" of the recently formed Scottish Police Services Authority and to convey a strong message to the Scottish Government that officers are opposed to the creation of a single national force.

The suggested pay increase is to be put forward by the Northern joint branch board. Its stated aim is to: "Pursue through whichever mechanism available, a minimum 15% pay increase for all federated ranks".

The news comes as police officers in England and Wales announced plans to launch a High Court challenge to the Home Secretary's decision effectively to limit last year's pay award to 1.9%.

Their judicial review application, due to be held over two days, is being heard by Lord Justice Keene and Mr Justice Treacy in London.

Police Federation lawyers have said that forces around the country had a "legitimate expectation" that they would receive the full 2.5% increase recommended by an independent arbitration tribunal.

Jacqui Smith, the Home Secretary, decided in December not to backdate the 2.5% award recommended by the pay tribunal to September 1, the beginning of the police pay year, leading to the reduced increase of only 1.9%.

More than 22,000 off-duty officers marched through Westminster in January to protest against the pay deal in the biggest gathering of police officers in Britain's history.

In December, the Scottish Government revealed it would split with Westminster over police pay. While Ms Smith was being accused of reneging on the deal, Scottish ministers agreed to abide by the 2.5% pay increase agreed.

The move, which proved popular with officers north of the border, exacerbated the political rift with Westminster.

Despite the increase, Scottish police have said they will support colleagues south of the border. The challenge is being brought in the name of the staff side of the Police Negotiating Board (PNB).

The federation, which is being joined by police superintendents and chief police officers in mounting the legal action, claims Ms Smith had no power to overrule the pay tribunal unless it was necessary for reasons of "utmost national importance".

Another ground of challenge will be that Ms Smith's decision was "procedurally defective" and was an "abuse of the PNB process" by failing to tell the federation before announcing her decision.

The action also claims that officers' human rights are being infringed - in this case a right to freedom of association - because the police have given up the right to strike over pay.