Heineken may have to wait another three months to close its purchase of Scottish & Newcastle's operations in Ireland.

The Netherlands-based brewer has been informed by Ireland's Competition Authority (ICA) that it will progress its investigation into Heineken's purchase of S&N's Beamish & Crawford unit in the country to s "full (phase two) investigation".

The ICA said it was reviewing the transaction following a decision by the European Commission earlier this year to partially refer the merger to the Irish regulator. "The Competition Authority is required ... to determine whether the result of the proposed acquisition will "substantially lessen competition" in markets for goods or services in the state," the ICA noted.

Heineken, which was advised in April that the ICA was considering the Irish side of the transaction, could benefit from the possible creation of a duopoly in the Irish on-trade market, with Guinness owner Diageo.

When contacted by just-drinks, a spokesperson for Heineken confirmed that the company had been made aware of the news. "We will continue to co-operate with the authorities throughout this process," the spokesperson said.

The deadline for a final decision from the ICA is 3 November, although the regulator said the investigation may be concluded before the deadline.