IRN-Bru manufacturer AG Barr has signalled it is moving closer to a deal with larger rival Britvic, as the pair continue long-running merger talks.

AG Barr, based at Cumbernauld in North Lanarkshire, said in a joint statement with Britvic to the stock market yesterday: "Substantial progress has been made and the two parties are now at an advanced stage of discussions, which are ongoing."

They gave this update as they revealed the Takeover Panel had agreed to extend the deadline for them to announce whether or not they intend to merge until November 28.

This is the pair's second extension. They had announced on October 3 that they had obtained the Takeover Panel's consent to extend the deadline until yesterday, having revealed on September 5 they were in merger talks

They said on October 3: "Discussions are still ongoing."

Yesterday's references to "substantial progress" and to discussions being at an "advanced stage" would appear to signal the pair are much closer to a deal than they were on October 3.

Roger White, chief executive of AG Barr, declined to be drawn in September when asked by The Herald about analyst comments that the headquarters of a combined entity could be located at his company's Cumbernauld base. The issue of head office location is an important one for corporate Scotland, given the scale of AG Barr and a backdrop of a contraction of the publicly quoted company base north of the Border in recent years.

Shares in AG Barr fell by 3p or 0.7% to 445p in the wake of the update on the talks, giving the Scottish company a stock market worth of £520 million.

Britvic shares fell 0.8p or 0.2% to 359.2p, giving the Hertfordshire-based company a market capitalisation of about £870m.

When AG Barr and Britvic said on September 5 that they were in preliminary merger talks, they said that Mr White would become chief executive of the enlarged company if a deal were to go ahead.

The companies said at that stage it had been agreed that Britvic shareholders would own 63%, and AG Barr investors 37%, of a merged entity, and disclosed the talks had resulted from an approach by the Scottish company to its sector stablemate.