SNP ministers have demanded that Boris Johnson drop the words 'Britain' or 'UK' from the branding of a nationwide cultural festival being planned for 2022.
Whitehall insiders said the Scottish Government had also objected to 'British' being included in title or promotional material for the celebration of the "very best of modern Britain."
The row is said to have delayed the Department of Culture, Media and Sport (DCMS) commissioning around £3 million of work from creative agencies tasked with drawing up the material.
UK Government sources said the SNP's stance was "incredibly petty and hugely frustrating", with the festival expected to give Scotland's struggling cultural sector a £12 million boost.
Talks with the Scottish Government are now said to have stalled over planning for the event, which was envisaged as a successor to the hugely popular 1951 Festival of Britain.
Theresa May announced the festival at the 2018 Tory conference with a prediction it would strengthen "our precious Union", and Mr Johnson wants to use it to boost national morale following the Covid-19 pandemic.
It also emerged the Prime Minister is planning his third trip in three months to Scotland next month, with polls showing a small majority for independence.
Chancellor Rishi Sunak will also make another visit north of the Border later this year as part of a UK Government 'charm offensive'. The Treasury is currently supporting 930,000 Scottish jobs through furlough and funding for the self-employed.
The Government is drawing up plans for 10 events as part of the 2022 festival, including one in Scotland, that would include spectacular performances akin to those seen in the 2012 London Olympic Games opening ceremony.
It will also celebrate the UK's achievements in science, engineering and technology as Mr Johnson seeks to strike new trade deals after Brexit.
A source told the Scottish Mail on Sunday: "We want to create a festival that showcases the very best of modern Britain but the Scottish Government are causing unnecessary delays because they want to remove all references to Britain or the UK when we launch the next phase.
"All parts of the UK should be working together to deliver something that we can all be proud of."
Maurice Golden, the Scottish Tories' Shadow Culture Secretary, said that more funding to celebrate Scotland and the UK's shared culture was "indisputably" positive "but, as usual, the SNP is playing petty, nationalist politics."
The Scottish Government did not say whether ministers had asked for the words 'UK' and 'Britain' to be removed from the festival.
A spokesman said: "We have been engaging positively since very early in the process on this issue and had several meetings with the Director Martin Green and with the UK government and any suggestion to the contrary is unfounded.
“We are currently working constructively with the UK Government and the other devolved nations on plans for the festival."