British troops accused of the unlawful killing and ill-treatment of civilians while at war in Iraq were governed by Europe's human rights convention at the time, the European Court of Human Rights has ruled.
The verdict from the court in Strasbourg dismissed claims by the UK government that soldiers were not subject to convention requirements because they were beyond its jurisdiction at the time.
The judges declared that, in the "exceptional circumstances" when UK forces assumed responsibility for security in parts of Iraq, they remained under the jurisdiction of rules obliging signatory member states - including the UK - to safeguard the right to life and liberty.
The landmark judgment overturns a House of Lords majority ruling four years ago that there was no UK human rights jurisdiction regarding the deaths or wrongful detention of six civilians whose relatives took their cases to court.
In a seventh case - the death of hotel receptionist Baha Mousa - the Lords had accepted UK responsibility under the convention, because the victim was in a British military building in Basra at the time of the alleged brutality which led to his death.
The Strasbourg judgment effectively extends the remit of the convention, declaring: "Following the removal from power of the Ba'ath regime and until the accession of the Iraqi Interim Government, the UK (together with the US) assumed in Iraq the exercise of some of the public powers normally to be exercised by a sovereign government.
"In particular, the UK assumed authority and responsibility for the maintenance of security in South East Iraq.
"In the exceptional circumstances deriving from the UK's assumption of authority for the maintenance of security in South East Iraq from 1 May 2003 to 28 June 2004, the UK had jurisdiction under Article 1 (obligation to respect human rights) of the European Convention on Human Rights in respect of civilians killed during security operations carried out by UK soldiers in Basra."
The judgment also found the UK guilty of "a failure to conduct an independent and effective investigation into the deaths of the relatives of five of the six applicants, in violation of Article 2 (right to life) of the Convention."
An MoD spokeswoman said: "We are disappointed by these Strasbourg judgments and we will consider them in detail before deciding on our next steps."