A critical report into stop and search has been delayed after a draft of the dossier was sent to Police Scotland and the Government for fact-checking.

HM Inspectorate of Constabulary in Scotland (HMICS) was to unveil its investigation last week but the publication date was mysteriously put back.

The use of stop and search, a signature policy of chief constable Stephen House, has been dogged by controversy over the last twelve months.

Frisk levels are far higher proportionately than in the Metropolitan police, most searches have no legal basis, and young children have been stopped after supposedly providing consent.

HMICS, established to monitor the force's effectiveness, launched its probe in October.

The investigation followed reports in the Sunday Herald that police officers, under pressure to increase the number of searches, were entering 'bogus' frisks into the national database.

The six-month exercise has been completed and the report is believed to make unhappy reading for House and his senior colleagues.

Derek Penman, the most senior HMICS figure, told MSPs on March 19 that the report would be available in the next week.

However, HMICS performed a u-turn after sending the report to Police Scotland, the Scottish Government, the Scottish Police Authority, the Metropolitan Police and other stakeholders.

The watchdog invited the bodies to provide comment on the facts contained in the report, but the delay has sparked concerns of interference.

HMICS is based at St Andrews House in Edinburgh, home to the Scottish Government.

Asked whether the force had queried any of the facts or findings in the HMICS report, a Police Scotland spokesperson said: "We confirm receipt of a fact-checking copy as standard practice and offer no further comment as the document has not yet been published by HMICS."

A spokeswoman for HMICS said: "HMICS indicated its aim to publish the report on March 27, 2015. However given the complexity of the report, there have been delays in the response to the factual accuracy and we are still progressing the final version of the report with a view to publishing on Tuesday, March 31."

Scottish Liberal Democrat MSP Alison McInnes said: "Given how controversial the use of stop and search is, the public need to have confidence that this report on the use of the tactic will be rigorous and wholly independent."

Tory MSP John Lamont said: "It's very telling that this important report has been held back a week.

"We want stop and search to remain a valuable tool to detect and deter crime, but to achieve this objective the process has to be transparent and accountable.

"If the force is going to earn people's trust we need a fundamental review of stop and search, with no delays."