The firm contracted to run Scotland's census has been cleared to work for the Scottish Government, despite allegations of human rights abuse against its parent company.

Campaign groups have been alarmed at the award of a £18.5m contract to CACI (UK), a subsidiary of CACI International, which is accused of torturing Iraqi prisoners at Abu Ghraib prison in Baghdad.

The procurator fiscal in Edinburgh has been looking at whether allegations of crimes committed by companies overseas could be pursued as a criminal prosecution in a Scottish court.

However, the Crown Office has considered and rejected a report passed from Lothian and Borders Police over the firm's human rights record.

It had been argued that CACI's alleged conduct could be investigated in Scotland under the Geneva Conventions Act 1957 and the Geneva Conventions (Amendment) Act 1995, which attempt to afford domestic courts universal jurisdiction for "grave breaches" of humanitarian law.

This includes wilful killing, torture or inhuman treatment and wilfully causing great suffering or serious injury to body or health which was not justified by military necessity and was carried out unlawfully and wantonly.

The Scottish Government has previously said it would never be party to a contract with any firm "convicted" of human rights abuses, and insisted it was "fundamentally committed to ethical conduct".

A government spokesman said the General Register Office of Scotland (GROS) "could not take unproven allegations into consideration".

Part of the report submitted to the Crown Office is understood to include a US ruling which concluded that four former Abu Ghraib detainees, who were tortured and later released without charge, can sue CACI International.

In March US Judge Gerald Bruce Lee denied a motion by the Virginia-based company, a major contractor to the US Defence Department, to dismiss the detainees' claims.

A Crown Office spokeswoman said: "A formal request was made by a resident in West Lothian for the procurator fiscal at Linlithgow to investigate allegations of war crimes at the Abu Ghraib prison in Iraq.

"The Crown have no jurisdiction to investigate the allegations made as they refer to foreign nationals on foreign soil and therefore the file has been returned."