Correspondence released to The Scotsman under freedom of information legislation shows that the Scottish and UK governments have been at odds over who is responsible for reserving venues.
The two administrations have forged an uneasy alliance since it was announced the United Nations conference would be coming to Glasgow.
Last year, a war of words broke out over the use of the Glasgow Science Centre, a venue which was first booked by Scottish ministers. It escalated after Claire O’Neill, the former president of the summit, said there was a “complete stand-off” between two governments.
She accused the SNP administration of behaving “disgracefully” by contracting buildings at the COP26 site, and said Prime Minister Boris Johnson had "heartily and saltily" rejected her proposal for First Minister Nicola Sturgeon to be given an official role at the summit.
Ms O’Neill, who now works for the World Business Council For Sustainable Development, called for an end to the “playground politics” which threatened to overshadow the biggest and most complex event ever hosted on Scottish soil.
Since then, both governments have attempted to show a united front, with Scottish ministers agreeing to transfer control of the science centre to their UK counterparts for use during the conference.
But the heavily redacted correspondence disclosed by the Scottish Government shows that the relationship is far from harmonious.
An email sent in February by an official at the COP26 unit - a dedicated team in the Cabinet Office tasked with organising the summit - questioned why the Scottish Government was looking to make its own arrangements for venues.
It noted that Glasgow Museums had received an enquiry via the agency, ExecSpace, “looking for venues for Scottish Government events during COP26,” and reminded the Scottish Government that “most of the premier venues in the city have been provisionally reserved for the event delivery partners,” including Scottish ministers.
The email, sent by the COP26 unit’s event operations manager, added: “Can I please ask that any enquiries for venue space in relation to COP are coordinated and directed through one point of contact to avoid any miscommunication or additional work for our teams.”
The following month, an official at the Scottish Government’s COP26 operations and delivery team wrote to the COP26 unit, asking if it was possible to sign a contract on a new venue and pay a deposit.
But the reply, sent six days later, said that “it is not reasonable” to expect that the contracts would be signed by the end of that month.
The unit’s event operations manager stressed that it needed “a significant amount more detail” from Scottish ministers in order to develop costs and a contract.
It added: ”There is a huge demand of venue use requests from partners and other stakeholders. I did try to prioritise SG however didn’t receive any correspondence for a few months.”
The Scottish Government initially failed to respond to The Scotsman’s FOI request. It only did so after a request for an internal review.
Its disclosure said certain information was exempt for the purposes of “safeguarding national security,” citing evidence of threats from extremists and terrorists at previous high profile summits and COPs.