Analysts at Jefferies said the recent management change at BG presented the opportunity to refocus the company and predicted investors would welcome the sale of the North Sea assets at the right price.
In a note to clients, analysts at the investment bank valued BG's North Sea assets at around $6.6 billlion (£4.2bn).
The Jefferies analysts said while BG has generated lots of cash from the portfolio, the company has experienced problems on some assets. These impacted on production levels in the year to December 31.
The assets include a 14% stake in the Elgin Franklin development, which was shut in by Total following a gas leak in March last year.
BG could use the funds from selling what Jefferies judges to be the non-core UK portfolio to help grow its operations in areas such as Brazil and Australia.
"While we recognise the importance of the cash-flows from the UK, we deem the assets non-core to the essence of BG, therefore a future candidate for disposal," said Jefferies.
However, Neil Burrows, head of global media at BG, told The Herald: "Our commitment to the UK North Sea is undiminished."
Mr Burrows noted that the management presentation which accompanied BG's annual results announcement on Tuesday demonstrated the value of North Sea production to the company and how it plans to improve performance.
In his first annual results presentation since succeeding Frank Chapman as chief executive on January 1, Chris Finlayson said: "The UK assets have continued to create significant value for BG Group. Over the past five years they have delivered $12bn of operating profit and we have added around 200 mmboe [million barrels of oil equivalent] of discovered reserves and resources."
Mr Finlayson said BG is planning a big maintenance campaign on the Everest and Lomond fields in 2014 and 2015 after achieving big efficiency improvements on the Armada development.
"With production restored from Elgin Franklin and new production from Jasmine we expect our UK production to be higher in 2013 than 2012," added Mr Finlayson.
Total submitted a revised safety case to the Health and Safety Executive in November with a 90-day deadline for final responses from the agency. The company hopes acceptance of the safety case would be the final stage in the process of preparing to restart Elgin Franklin.