The Exchange cut its data feed at 2pm on Friday, just four hours after ESI and ShareLink, the Birmingham-based retail brokerage, launched a share- dealing service in which prices for 4,461 shares were displayed on a "site" of the Internet's worldwide web.
An OFT spokesman said: "ESI has asked us if we will look into it. We have to consider if it is in our jurisdiction and whether it is an issue for us."
ShareLink and ESI are also consulting lawyers to see if they have any legal recourse under the contract, which had been due to run for one year. ESI's technical director, Jack Lang, says the Exchange told him in a letter that the price feed was cut because ESI had publicised its contract in the media.
"There's a general clause in the contract about publicity, but they announced that they were changing its terms just before last week's launch," Mr Lang said yesterday. The Exchange declined to comment on its reason for suspending the feed.