MPs have criticised the UK Government for failing to advise Scottish ministers of plans to include the Lockerbie bomber in a prisoner transfer agreement with Libya.
The Commons' Scottish Affairs Committee said the lack of communication was "regrettable" following an inquiry into relations between the administrations in Edinburgh and London.
North-south working practices were illustrated in a case study on former prime minister Tony Blair's "deal in the desert" with Libyan leader Muammar Gaddafi in 2007.
Abdelbaset Al Megrahi, the man convicted for the Pan-Am bombing which claimed 270 lives in 1988, eventually had a prisoner transfer application rejected by the Scottish Government but was released to his home country on compassionate grounds in August last year.
The SNP Government at Holyrood has previously attacked a lack of information from UK ministers on the prisoner transfer agreement.
First Minister Alex Salmond told the committee in January that Mr Blair's deal was a "mistake" that cut across Scots law.
In its report, the committee said a concordat on international relations clearly showed that the UK Government should provide Scottish ministers with information.
The report added: "Although the concordat is not a legally binding document, we conclude that it was regrettable that the UK Government did not advise the Scottish Executive of the terms of the memorandum of understanding between Libya and the United Kingdom relating to the devolved matter of justice prior to signing."
The UK Government "must consider" whether confidentiality outweighs that responsibility in future, particularly when Scottish ministers will have to make "highly emotive" decisions, the report continued.
A Scotland Office spokesman said: "It is important to be clear that no deal was signed to return Megrahi - that was always, rightly, the prerogative of Scottish Ministers."