A planned merger between the UK's leading football pools firms has been referred to the Competition Commission.
Pools players spend almost £80m a year, the OFT says
The Office of Fair Trading (OFT) said it referred the Littlewoods-Vernons Pools deal as it feared the merger would create a monopoly.
Littlewoods Pools owner Sportech said in March it had entered exclusive talks to buy Vernons Pools from Ladbrokes.
Liverpool-based Sportech said it was disappointed with the decision and was now considering what action to take.
Competition watchdogs said the deal would give Sportech - which already owns the Zetters pools brands - a 99% share of the football pools market.
Sportech bought the Zetters business in 2002 and that deal was passed by competition authorities.
The planned deal for Vernons would give Sportech access to more than 750,000 weekly pools players who spend about £80m a year, the OFT said.
As a result the OFT said it was concerned that it would leave players at risk of higher prices or lower pay-out ratios.
The Competition Commission has asked for the views of "all interested parties" and is expected to announce its decision by 17 October.