UPDATE 1-Britvic, A.G. Barr get more time to decide on merger

* "Put up or shut up" deadline extended to Oct. 31

* Companies seek extension to consider aspects of merger

(Adds background, share movement)

Oct 3 (Reuters) - British soft drinks group Britvic and Irn-Bru maker AG Barr have been given more time to decide on the 1.3 billion pound ($2.10 billion) merger.

The deadline for the companies to table a firm bid or end talks has been extended to Oct. 31. It was to expire on Wednesday.

AG Barr declined to comment beyond Wednesday morning's statement. Britvic, which makes and sells PepsiCo brands in Britain and Ireland, could not immediately be reached for comment.

The companies disclosed last month they were in talks on a merger, which would transfer 37 percent of the enlarged group to shareholders of the smaller AG Barr.

With Britvic in play, speculation rose that it could attract interest from private equity buyers or key shareholder PepsiCo.

Britvic and A.G. Barr have suffered from poor weather this year but Britvic, which makes Tango and J20, has had a torrid time in particular.

The company was forced to recall one of its top brands, Robinsons Fruit Shoot, over faulty caps in July.

AG Barr, best known for its bright orange Irn-Bru drink and exotic juice brand Rubicon, reported an 8 percent fall in half-year profit last week.

Britvic shares were down 1 pence at 365 pence at 0740 GMT on the London Stock Exchange on Wednesday.

Shares in AG Barr closed at 454 pence on Tuesday.

Britvic shares have gained 12 percent since the announcement of merger talks while A.G. Barr rose 9 percent.

($1 = 0.6196 British pounds)

(Reporting by Abhishek Takle in Bangalore; Editing by Don Sebastian)

((abhishek.takle@thomsonreuters.com)(within UK +44 20 7542 1810)(outside UK +91 80 4135 6102)(Reuters Messaging: abhishek.takle.thomsonreuters.com@reuters.net))