The UK’s competition watchdog has launched a formal investigation into the £3.3bn takeover of the UK soft drinks maker Britvic by the Danish brewer Carlsberg.

The Competition and Markets Authority (CMA) has set a deadline of 18 December for the first phase of its investigation into the deal.

Britvic – maker of brands including Robinsons squash, J20 and R White’s lemonade – accepted a £13.15-a-share offer from Carlsberg in July.

This came after it had rejected previous takeover offers from Carlsberg on the grounds that they undervalued the company.

Carlsberg has said the deal would allow it to combine Britvic’s soft drinks products with its own beer offering, creating a beverage “powerhouse” in the UK and elsewhere in Europe.

The regulator said in September it was looking into whether the deal could reduce competition in the UK market, and has now decided to launch a formal investigation.

After the December deadline, the CMA will decide whether to conduct an in-depth phase 2 investigation into the deal or give it the green light.

A spokesperson for Carlsberg said the CMA’s investigation was “a normal process that was expected, and we look forward to working constructively with the CMA as it progresses”.

They added: “We believe that the combination of Carlsberg’s business with Britvic will create a highly attractive multi-beverage supplier, benefiting from an efficient supply chain and distribution network, and providing customers with a portfolio of market-leading brands and leading customer service.”

Provided the deal is approved by the regulator and other conditions are satisfied, the brewer hopes to complete the transaction in the first quarter of 2025.

Carlsberg hopes to find annual cost savings of about £100m over five years through the deal, including through procurement and supply chain efficiencies as well as economies in administration and overheads.

Britvic, headquartered in Hemel Hempstead, Hertfordshire, was founded in the UK in the 1930s as the British Vitamin Products Company and used soft drinks as an affordable way of supplying vitamins to consumers. It has 39 brands in 100 countries including Brazil, France and Ireland.

It also has an exclusive licence with PepsiCo in Great Britain and Ireland to make and sell Pepsi Max, 7UP, Rockstar Energy and Lipton Ice Tea.

Carlsberg said previously it had secured an agreement from PepsiCo to waive a clause in its bottling contract with Britvic that would have allowed it to cancel the arrangement on the event of a change of ownership.

In June, Britvic rejected a £3.1bn takeover bid by Carlsberg, saying it undervalued the company, before accepting an improved offer the following month.

Britvic is also well known for its Robinsons brand, which had a prominent sponsorship partnership with the Wimbledon tennis tournament that was one of the longest-running in sport, and lasted for 86 years before it ended in 2022. Robinsons had been an independent company until it was acquired by Britvic in 1995.

Britvic declined to comment.