Johnson made the remarks during his day-long trip to Scotland on Thursday, which widely seen as part of a "charm offensive" following polls that indicated a rise in support for Scotland's independence after Brexit, reports Xinhua news agency. 

"I think endless talk about a referendum without any clear description of what the constitutional situation would be after that referendum is completely irrelevant now to the concerns of most people," he told the BBC. 

"We don't actually know what that referendum would set out to achieve... We don't know what the point of it would be -- what happens to the army, what happens to the Crown, what happens to the pound, what happens to the Foreign Office," he said. 

"Nobody will tell us what it's all meant to be about." 

The Prime Minister stressed that the priority right now should be "fighting this pandemic and coming back more strongly together", rather than arguing about the Constitution. 

Johnson started his trip to Scotland by visiting the Lighthouse Laboratory in Glasgow which processes coronavirus tests, before meeting troops who are setting up a vaccination centre in the city. 

He also toured the Valneva vaccine factory in Livingston, which is expected to deliver 60 million doses to Britain by the end of the year if the jab is approved. 

The Prime Minister praised the "amazing performance" of the Scottish people for their efforts to fight the pandemic. 

Ahead of his trip, Johnson said the great benefits of cooperation across the whole of the UK "have never been clearer than since the beginning of this pandemic". 

"We have pulled together to defeat the virus, providing 8.6 billion pounds ($11.76 billion) to the Scottish government to support public services whilst also protecting the jobs of more than 930,000 citizens in Scotland. 

"We have a vaccine programme developed in labs in Oxford being administered across the UK by our armed forces, who are helping to establish 80 new vaccine centres across Scotland... That's how we are delivering for the people of Scotland so we can ensure the strongest possible recovery from the virus," he added. 

Johnson's visit to Scotland came amid growing calls for another Scottish independence referendum after Brexit. 

Majority of the Scottish people chose to stay in the European Union (EU) in the 2016 Brexit referendum. 

In 2014, people in Scotland voted by a majority to remain part of the UK in what was described as a once-in-a-generation poll. 

Scotland's First Minister Nicola Sturgeon has said that she will push for a second referendum on independence if her Scottish National Party wins a majority in May's parliament elections. 

Meanwhile, Sturgeon also labelled Johnson's Scotland trip as "not essential" since strict travel restrictions were in place. 

Speaking ahead of the Prime Minister's visit, Sturgeon said: "I would say me travelling from Edinburgh to Aberdeen to visit a vaccination centre right now is not essential, and Boris Johnson travelling from London to wherever he is in Scotland to do the same is not essential. 

"If we're asking other people to abide by that, then I'm sorry but it's probably incumbent on us to do likewise." 

In response, Downing Street defended Johnson's visit, saying that it was important for the Prime Minister to be "visible and accessible" across the whole of Britain during the pandemic. 

Opposition Labour leader Keir Starmer also backed Johnson's visit to Scotland. 

"He is the Prime Minister of the UK. It's important that he travels to see what is going on, on the ground," he told LBC Radio. 

England is currently under the third national lockdown since the outbreak of the pandemic in the country. 

Similar restriction measures are also in place in Scotland, Wales and Northern Ireland.